iRhythm (IRTC) 10-K 31 Mar 17 2016 FY Annual report Financial data

Document and Entity Information

Document and Entity Information - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Feb. 28, 2017	Jun. 30, 2016
Document And Entity Information [Abstract]
Document Type	10-K
Amendment Flag	false
Document Period End Date	Dec. 31, 2016
Document Fiscal Year Focus	2,016
Document Fiscal Period Focus	FY
Trading Symbol	IRTC
Entity Registrant Name	iRhythm Technologies, Inc.
Entity Central Index Key	1,388,658
Current Fiscal Year End Date	--12-31
Entity Well-known Seasoned Issuer	No
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Filer Category	Smaller Reporting Company
Entity Common Stock, Shares Outstanding		22,152,637
Entity Public Float			$ 314

Consolidated Balance Sheets

Consolidated Balance Sheets - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Current assets:
Cash and cash equivalents	$ 51,643	$ 25,208
Short-term investments	54,407
Accounts receivable, net	9,406	5,577
Inventory	1,390	1,145
Prepaid expenses and other current assets	1,671	808
Restricted cash	91	91
Total current assets	118,608	32,829
Investments, long-term	10,981
Property and equipment, net	4,653	2,036
Goodwill	862	862
Other assets	3,052	2,145
Total assets	138,156	37,872
Current liabilities:
Accounts payable	2,103	1,459
Accrued liabilities	10,165	6,699
Deferred revenue	947	506
Accrued interest, current portion		111
Total current liabilities	13,215	8,775
Debt	32,227	30,552
Deferred rent, noncurrent portion	26	28
Accrued interest, net of current portion	126	96
Preferred stock warrant liabilities		2,949
Total liabilities	45,594	42,400
Commitments and contingencies (Note 7)
Convertible preferred stock, $0.001 par value – zero and 11,392,882 shares authorized at December 31, 2016 and 2015, respectively; zero and 11,046,146 shares issued and outstanding at December 31, 2016 and 2015, respectively; aggregate liquidation preference of $0, and $117,495 at December 31, 2016 and 2015, respectively		97,096
Stockholders’ equity (deficit):
Preferred stock, $0.001 par value – 5,000,000 and zero shares authorized at December 31, 2016 and 2015, respectively; and none issued and outstanding at December 31, 2016 and 2015, respectively
Common stock, $0.001 par value – 100,000,000 and 18,528,913 shares authorized at December 31, 2016 and 2015, respectively; 22,139,346 and 1,410,565 shares issued and outstanding at December 31, 2016 and 2015, respectively	22	1
Additional paid-in capital	219,718	4,641
Accumulated other comprehensive loss	(9)
Accumulated deficit	(127,169)	(106,266)
Total stockholders’ equity (deficit)	92,562	(101,624)
Total liabilities, convertible preferred stock and stockholders’ equity (deficit)	$ 138,156	$ 37,872

Consolidated Balance Sheets (Pa

Consolidated Balance Sheets (Parenthetical) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Temporary equity, shares authorized		11,392,882
Temporary equity, shares issued		11,046,146
Temporary equity, shares outstanding		11,046,146
Temporary equity, liquidation preference		$ 117,495
Preferred stock, par value	$ 0.001	$ 0.001
Preferred stock, shares authorized	5,000,000	0
Preferred stock, shares issued	0	0
Preferred stock, shares outstanding	0	0
Common stock, par value	$ 0.001	$ 0.001
Common stock, shares authorized	100,000,000	18,528,913
Common stock, shares issued	22,139,346	1,410,565
Common stock, shares outstanding	22,139,346	1,410,565
Convertible Preferred Stock
Temporary equity, par value	$ 0.001	$ 0.001
Temporary equity, shares authorized	0	11,392,882
Temporary equity, shares issued	0	11,046,146
Temporary equity, shares outstanding	0	11,046,146
Temporary equity, liquidation preference	$ 0	$ 117,495

Consolidated Statements of Oper

Consolidated Statements of Operations - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Statement [Abstract]
Revenue	$ 64,072	$ 36,140	$ 21,749
Cost of revenue	20,883	14,700	10,591
Gross profit	43,189	21,440	11,158
Operating expenses:
Research and development	7,150	6,349	5,698
Selling, general and administrative	51,621	36,722	20,225
Total operating expenses	58,771	43,071	25,923
Loss from operations	(15,582)	(21,631)	(14,765)
Interest expense	(3,248)	(1,059)	(774)
Other expense, net	(2,073)	(109)	(293)
Net loss	$ (20,903)	$ (22,799)	$ (15,832)
Net loss per common share, basic and diluted	$ (3.95)	$ (16.57)	$ (12.05)
Weighted-average shares used to compute net loss per common share, basic and diluted	5,285,847	1,376,106	1,314,294

Consolidated Statements of Comp

Consolidated Statements of Comprehensive Loss - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Statement Of Income And Comprehensive Income [Abstract]
Net Loss	$ (20,903)	$ (22,799)	$ (15,832)
Other comprehensive loss:
Unrealized loss on available-for-sale securities	(9)
Comprehensive loss	$ (20,912)	$ (22,799)	$ (15,832)

Consolidated Statements of Conv

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Initial Public Offering	Convertible Preferred Stock	Convertible Preferred StockInitial Public Offering	Common Stock	Common StockInitial Public Offering	Additional Paid-In Capital	Additional Paid-In CapitalInitial Public Offering	Accumulated Deficit	Accumulated Other Comprehensive Loss
Balance at Dec. 31, 2013	$ (65,590)				$ 1		$ 2,044		$ (67,635)
Balance, Shares at Dec. 31, 2013					1,287,654
Balance, Convertible Preferred Stock at Dec. 31, 2013			$ 67,785
Balance, Convertible Preferred Stock, Shares at Dec. 31, 2013			7,680,417
Issuance of Series E convertible preferred stock for cash, net of issuance costs			$ 17,229
Issuance of Series E convertible preferred stock for cash, net of issuance costs, Shares			1,977,450
Issuance of common stock upon the exercise of options	$ 50						50
Issuance of common stock upon the exercise of options, Shares	38,982				38,982
Stock-based compensation expense	$ 828						828
Net loss	(15,832)								(15,832)
Balance at Dec. 31, 2014	(80,544)				$ 1		2,922		(83,467)
Balance, Shares at Dec. 31, 2014					1,326,636
Balance, Convertible Preferred Stock at Dec. 31, 2014			$ 85,014
Balance, Convertible Preferred Stock, Shares at Dec. 31, 2014			9,657,867
Issuance of Series E convertible preferred stock for cash, net of issuance costs			$ 12,082
Issuance of Series E convertible preferred stock for cash, net of issuance costs, Shares			1,388,279
Issuance of common stock upon the exercise of options	$ 309						309
Issuance of common stock upon the exercise of options, Shares	84,300				83,929
Stock-based compensation expense	$ 1,410						1,410
Net loss	(22,799)								(22,799)
Balance at Dec. 31, 2015	$ (101,624)				$ 1		4,641		(106,266)
Balance, Shares at Dec. 31, 2015	1,410,565				1,410,565
Balance, Convertible Preferred Stock at Dec. 31, 2015	$ 97,096		$ 97,096
Balance, Convertible Preferred Stock, Shares at Dec. 31, 2015	11,046,146		11,046,146
Issuance of common stock upon the exercise of options	$ 132				$ 1		131
Issuance of common stock upon the exercise of options, Shares	57,067				56,827
Issuance of preferred stock upon exercise of warrants			$ 457
Issuance of preferred stock upon exercise of warrants, Shares			31,359
Issuance of common stock in connection with initial public offering, net of offering costs	$ 110,721				$ 7		110,714
Issuance of common stock in connection with initial public offering, net of offering costs, Shares					7,238,235
Conversion of convertible preferred stock to common stock in connection with initial public offering		$ 97,553		$ (97,553)		$ 13		$ 97,540
Conversion of convertible preferred stock to common stock in connection with initial public offering, Shares				(11,077,505)		13,375,333
Conversion of convertible preferred stock warrants to common stock warrants in connection with initial public offering	4,821						4,821
Issuance of common stock upon net exercise of warrants, Shares					58,386
Stock-based compensation expense	1,871						1,871
Net loss	(20,903)								(20,903)
Unrealized loss on investments	(9)									$ (9)
Balance at Dec. 31, 2016	$ 92,562				$ 22		$ 219,718		$ (127,169)	$ (9)
Balance, Shares at Dec. 31, 2016	22,139,346				22,139,339
Balance, Convertible Preferred Stock at Dec. 31, 2016			$ 0
Balance, Convertible Preferred Stock, Shares at Dec. 31, 2016			0

Consolidated Statements of Con7

Consolidated Statements of Convertible Preferred Stock and Stockholders' Equity (Deficit) (Parenthetical) - Convertible Preferred Stock - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Issuance of Series E convertible preferred stock for cash, per share	$ 8.77	$ 8.77
Issuance of Series E convertible preferred stock for cash, issuance costs	$ 92	$ 115

Consolidated Statements of Cash

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Cash flows from operating activities
Net Loss	$ (20,903)	$ (22,799)	$ (15,832)
Adjustments to reconcile net loss to net cash used in operating activities:
Depreciation and amortization	568	492	242
Stock-based compensation	1,871	1,410	828
Amortization of debt discount and issuance costs	251	116	111
Amortization (accretion) on investments	6
Loss on disposal of assets		10	7
Change in accrued interest		(64)	(89)
Provision for bad debt and contractual allowance	4,686	1,557	401
Change in fair value of preferred stock warrant liabilities	2,123	111	291
Non-cash interest expense	1,481
Changes in operating assets and liabilities:
Accounts receivable	(8,515)	(1,281)	(2,565)
Inventory	(245)	(327)	(71)
Prepaid expenses and other current assets	(863)	(506)	(35)
Other assets	(1,235)	(491)	(1,166)
Accounts payable	305	132	703
Accrued liabilities	3,380	3,522	1,399
Deferred rent	(2)	28	(28)
Deferred revenue	441	85	178
Net cash used in operating activities	(16,651)	(18,005)	(15,626)
Cash flows from investing activities
Purchases of property and equipment	(2,763)	(1,787)	(539)
Purchases of available-for-sale investments	(65,403)
Net cash used in investing activities	(68,166)	(1,787)	(539)
Cash flows from financing activities
Proceeds from issuance of common stock upon exercise of stock options, net of repurchases	132	309	50
Proceeds from issuance of common stock upon exercise of warrants	206
Proceeds from issuance of convertible preferred stock, net of issuance costs		12,134	17,229
Payments of deferred offering costs	(3,522)	(5)
Proceeds from long-term debt, net of debt discount and issuance costs		29,018	4,905
Repayments of long-term debt		(4,905)	(4,500)
Proceeds of issuance of common stock upon initial public offering	114,436
Net cash provided by financing activities	111,252	36,382	17,684
Net increase in cash and cash equivalents	26,435	16,590	1,519
Cash and cash equivalents, beginning of year	25,208	8,618	7,099
Cash and cash equivalents, end of year	51,643	25,208	8,618
Supplemental disclosures of cash flow information
Interest paid	1,591	343	318
Non-cash investing and financing activities
Issuance of warrants to purchase preferred stock		44	$ 98
Property and equipment included in accounts payable	423
Deferred offering costs included in accounts payable and accrued liabilities	188	265
Conversion of preferred stock to common stock	97,553
Conversion of preferred stock warrants to common stock warrants	$ 4,821
Convertible Preferred Stock
Non-cash investing and financing activities
Series E convertible preferred stock issuance costs included in accrued liabilities		52
Revolving Line of Credit
Cash flows from financing activities
Payments of issuance costs for revolving line of credit		$ (169)

Organization and Description of

Organization and Description of Business	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Organization and Description of Business	1. Organization and Description of Business iRhythm Technologies, Inc. (the “Company”) was incorporated in the state of Delaware in September 2006. The Company is a commercial-stage digital healthcare company redefining the way cardiac arrhythmias are clinically diagnosed by combining wearable biosensing technology with cloud-based data analytics and machine-learning capabilities. The Company commenced commercial introduction of its products in the United States in 2009 following clearance by the U.S. Food and Drug Administration. The Company’s headquarters are based in San Francisco, California, and the Company has manufacturing facilities in Cypress, California, and clinical centers in Lincolnshire, Illinois and Houston, Texas. In March 2016, the Company formed a wholly-owned subsidiary in the United Kingdom. The Company manages its operations as a single operating segment. Substantially all of the Company’s assets are maintained in the United States. The Company derives substantially all of its revenue from sales to customers in the United States, based upon the billing address of the customer. Reverse Stock Split On October 4, 2016, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of the Company’s issued and outstanding common stock at a 1-for- 5.882698 ratio, which was effected on October 5, 2016. The par value and authorized shares of common stock and convertible preferred stock were not adjusted as a result of the reverse split. All issued and outstanding common stock, options to purchase common stock and per share amounts contained in these consolidated financial statements have been retroactively adjusted to reflect the reverse stock split for all periods presented. Initial Public Offering The Company’s initial public offering (“IPO”) of 7,238,235 shares of common stock was effected through a registration statement on Form S-1 (Registration Nos. 333-213773 and 333-214179), which was declared effective on October 19, 2016. The initial public offering closed on October 25, 2016 and resulted in net proceeds of approximately $110.7 million, after deducting underwriting discounts and commissions of $8.6 million and other expenses of $3.7 million. In October 2016, immediately upon the Company’s sale of its common stock in the initial public offering

Summary of Significant Accounti

Summary of Significant Accounting Policies	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Summary of Significant Accounting Policies	2. Summary of Significant Accounting Policies Basis of Presentation The accompanying consolidated financial statements are consolidated for the year ended December 31, 2016 and include the accounts of iRhythm Technologies, Inc. and its wholly-owned subsidiary, iRhythm Technologies Ltd., established in March 2016. All intercompany accounts and transactions have been eliminated. All accompanying financial statements and disclosures for the years ended December 31, 2015 and December 31, 2014 include only the accounts of iRhythm Te chnologies, Inc. The financial statements of iRhythm Technologies Ltd. use the U.S. dollar as the functional currency Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, contractual allowances for revenue, allowance for doubtful accounts, the useful lives of property and equipment, the recoverability of long-lived assets including the estimated usage of the printed circuit board assemblies (“PCBAs”), the valuation of deferred tax assets, the fair value of the Company’s preferred and common stock and stock-based compensation. The Company bases these estimates on historical and anticipated results, trends, and various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. Actual results may differ from those estimates. Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, which includes cash equivalents, accounts receivable, prepaid expenses, accounts payable and accrued liabilities, approximate fair value due to their short maturities. Cash and Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market funds. Investments Short-term investments consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition. Long-term investments have maturities greater than 365 days as of the balance sheet date. All investments are carried at fair value based upon quoted market prices. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of accumulated other comprehensive loss. The cost of available-for-sale securities sold is based on the specific-identification method. Realized gains and losses are included in earnings, and are derived for specific-identification method for determining the costs of investments sold. Restricted Cash Restricted cash consists of certificates of deposit held with a financial institution as security deposits for building leases, and is included in current assets on the Company’s consolidated balance sheets. Accounts Receivable, Allowance for Doubtful Accounts and Contractual Allowance Accounts receivable consists of amounts due to the Company from institutions, government payors and commercial insurance payors as a result of the Company’s normal business activities. Accounts receivable is reported on the balance sheet net of an estimated allowance for doubtful accounts and contractual allowance. The Company establishes an allowance for doubtful accounts for estimated uncollectible receivables based on historical collections, review of specific outstanding claims, consideration of relevant qualitative factors and an established allowance percentage by aging category. The Company writes off amounts against the allowance for doubtful accounts when they are deemed to be uncollectible. Increases and decreases in the allowance for doubtful accounts are included as a component of selling, general and administrative expenses. The Company establishes a contractual allowance, which is a reduction in revenue, for estimated uncollectible amounts from Centers for Medicare & Medicaid Services (“CMS”), and contracted third-party commercial payors. The following table presents the changes in the allowance for doubtful accounts: December 31, December 2016 2015 Balance, beginning of year $ 1,125 $ 470 Add: provision for doubtful accounts 1,960 1,177 Less: write-offs, net of recoveries and other adjustments (1,293 ) (522 ) Balance, end of year $ 1,792 $ 1,125 The following table presents the changes in the contractual allowance: December 31, December 31, 2016 2015 Balance, beginning of year $ 338 $ 91 Add: contractual allowances 2,726 380 Less: write-offs, net of recoveries and other adjustments (724 ) (133 ) Balance, end of year $ 2,340 $ 338 Management reviews and updates its estimates for the allowance for doubtful accounts and the contractual allowance periodically to reflect its experience regarding historical collections. If management were to make different judgments or utilize different estimates in the allowance for doubtful accounts and the contractual allowance, differences in the amount of reported selling, general and administrative expenses and revenue could result, respectively. Concentrations of Risk Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents, investments and accounts receivable. Cash and cash equivalents and investments are deposited with one financial institution in the United States of America. At times, such deposits may be in excess of federally insured limits. Cash equivalents are invested in highly rated money market funds. The Company invests in a variety of financial instruments, such as, but not limited to, United States Government securities, corporate notes, commercial paper and, by policy, limits the amount of credit exposure with any one financial institution or commercial issuer. The Company has not experienced any material losses on its deposits of cash and cash equivalents or investments. Concentrations of credit risk with respect to accounts receivable are limited due to the large number of customers comprising the Company’s customer base and their dispersion across many geographies. The Company does not require collateral. The Company records an allowance for doubtful accounts when it becomes probable that a receivable will not be collected. Government agencies, including CMS and the Veterans Administration, accounted for 40%, 41% and 30% of the Company’s revenue for the years ended December 31, 2016, 2015 and 2014, respectively. Accounts receivable related to federal government agencies accounted for 27% and 30% at December 31, 2016 and 2015, respectively. Supply Risk The Company relies on single suppliers for the supply of its reusable printed circuit board assemblies, disposable housings, instruments and other materials used to manufacture the ZIO Patch and the adhesive that binds the ZIO Patch to a patient’s body. These components and materials are critical, and there would be a considerable delay in finding alternative sources of supply. Inventory Inventory is stated at the lower of cost or market, cost being determined on a standard cost basis for material costs and on actual cost basis for labor and overhead, which approximates actual cost on a first in, first out (“FIFO”) basis, and market being determined as the lower of replacement cost or net realizable value. The Company records write-downs of inventory that is obsolete or in excess of anticipated demand or market value based on consideration of product lifecycle stage, technology trends, product development plans and assumptions about future demand and market conditions. Actual demand may differ from forecasted demand, and such differences may have a material effect on recorded inventory values. Inventory write-downs are charged to cost of revenue and establish a new cost basis for the inventory. Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the assets, ranging from three to five years. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful lives of the assets. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized. Internal-Use Software The Company capitalizes costs related to internal-use software during the application development stage. Costs related to planning and post implementation activities are expensed as incurred. Capitalized internal-use software is amortized on a straight-line basis over the estimated useful life, which is up to five years. The Company evaluates the useful lives of these assets on an annual basis, and tests for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets. Capitalized internal-use software costs are classified as a component of property and equipment. Goodwill Goodwill represents the excess of the purchase price paid over the fair value of tangible and identifiable intangible net assets acquired in business combinations. Goodwill is tested for impairment on an annual basis and at any other time if events occur or circumstances indicate that the carrying amount of goodwill may not be recoverable. Such events or circumstances may include significant adverse changes in the general business climate, among other things. The impairment test is performed by determining the enterprise fair value of the Company, which is primarily based on the Company’s public market capitalization. If the Company’s carrying value, as a one reporting unit entity, is less than its fair value, then the fair value is allocated to all of its assets and liabilities (including any unrecognized intangible assets) as if the fair value was the purchase price to acquire the Company. The excess of the fair value over the amounts assigned to the Company’s assets and liabilities is the implied fair value of the goodwill. If the carrying amount of goodwill exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to that excess. The Company performs its annual evaluation of goodwill during the fourth quarter of each fiscal year. The Company did not record any charges related to goodwill impairment in any of the periods presented in these consolidated financial statements. Impairment of Long-Lived Assets The Company annually reviews long-lived assets for impairment or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future net cash flows which the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. To date, there have been no such impairments of long-lived assets. Other Assets Included in the other assets are printed circuit board assemblies, or PCBAs, totaling $2.8 million and $1.6 million as of December 31, 2016 and 2015, respectively. The Company uses a PCBA in each wearable device and it is used numerous times. Each time the PCBA is used in a wearable device, a portion of the cost of the PCBA is recorded as a cost of revenue. The Company has based its estimates of how many times a PCBA can be used on testing in research and development, loss rates, product obsolescence, and the amount of time it takes the device to go through the manufacturing, shipping, customer shelf and patient wear time and upload process. The Company periodically evaluates the use estimate. Deferred Offering Costs Deferred offering costs, which consisted primarily of legal, accounting, printer and filing fees related to the IPO, were capitalized. As of December 31, 2015, the Company capitalized $0.3 million of deferred offering costs in other long-term assets on the balance sheet. Deferred offering costs of $3.7 million were offset against IPO proceeds upon the completion of the offering in October 2016. Preferred Stock Warrant Liabilities The Company measured freestanding warrants to purchase shares of its convertible preferred stock at fair value, and recorded the related amounts as liabilities, because the shares underlying the warrants could obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The fair value of the preferred stock warrants was remeasured at each balance sheet date, and any change in fair value was included in earnings. Such charges were included in other expense, net in the consolidated statements of operations and comprehensive loss. In connection with the Company’s IPO, the Company remeasured the liability at the time of the IPO, and then reclassified the redeemable convertible preferred stock warrant liability to additional paid-in capital, as these warrants converted to common stock warrants. As of December 31, 2016, there were no convertible preferred stock warrants outstanding, and 217,245 common stock warrants were outstanding. Comprehensive Loss Comprehensive loss represents all changes in stockholders’ equity (deficit) except those resulting from and distributions to stockholders. The Company’s unrealized gains and losses on available-for-sale securities represent the only component of other comprehensive loss that are excluded from the reported net loss and that are presented in the consolidated statements of comprehensive loss. Revenue Recognition The Company’s devices, cardiac rhythm monitors, have a wear period for up to 14 days for the ZIO Patch or 30 days for the ZIO Event Card. The Company’s services, consisting of the delivery of reports containing analysis of data captured by the physical device to the prescribing physician, are generally billable at the start of the wear period or when reports are issued to physicians, depending on the service provided. For the ZIO Event Card, the Company recognizes revenue on a straight-line basis over the applicable wear period, as the event monitoring results are delivered to physicians. For the ZIO Service, the Company recognizes the revenue at the time that a report is delivered to a physician. For all services performed, the Company considers whether or not the following revenue recognition criteria are met: persuasive evidence of an arrangement exists and delivery has occurred or services have been rendered. For services performed for customers the Company invoices directly, additional revenue recognition criteria include that the price is fixed and determinable and collectability is reasonably assured; for customers in which the Company submits claims to third-party commercial and governmental payors for reimbursement, the Company recognizes revenue only when a reasonable estimate of reimbursement can be made. The assessment of whether a reasonable estimate of reimbursement can be made requires significant judgment by management. Where management’s judgment indicates a reasonable estimate of reimbursement can be made, revenue is recognized upon delivery of the patient report for the ZIO Service and straight-line for the ZIO Event Card. To date, the Company has not been able to estimate revenue for third-party payors for which it does not have a contracted rate, and therefore, revenue has been recognized on the earlier of notice or cash receipt. Some patients have out-of-pocket costs for amounts not covered by their insurance carrier, and the Company may bill the patient directly for these amounts in the form of co-payments and co-insurance in accordance with their insurance carrier and health plans. Some payors may not cover the Company’s service as ordered by the prescribing physician under their reimbursement policies. In the absence of contracted reimbursement coverage or the ability to reasonably estimate reimbursement, the Company recognizes revenue only upon the earlier of notification or when payment is received. The Company recognizes revenue related to billings for CMS and commercial payors on an accrual basis, net of contractual adjustments, when a reasonable estimate of reimbursement can be made. These contractual adjustments represent the difference between the list price (the billing rate) and the reimbursement rate for each payor. Upon ultimate collection from CMS and commercial payors, the amount is compared to the previous estimates and the contractual allowance is adjusted accordingly. Until a contract has been negotiated with a commercial payor, the Company’s services may or may not be covered by these entities’ existing reimbursement policies. In addition, patients do not enter into direct agreements with the Company that commit them to pay any portion of the cost of the service in the event that their insurance declines to reimburse the Company. In the absence of an agreement with the patient or other clearly enforceable legal right to demand payment from the patient, the related revenue is recognized only upon the earlier of notification of payment or when payment is received. Revenue recognized when cash or notification of coverage was received was $11.2 million, $3.5 million, and $0.6 million for the years ended December 31, 2016, 2015 and 2014, respectively. Revenue recognized on an accrual basis was $52.9 million, $32.6 million, and $21.2 million for the years ended December 31, 2016, 2015 and 2014, respectively. Certain of the Company’s customers pay the Company directly for the ZIO Service upon shipment of devices. Such advance payments are recorded as deferred revenue on the consolidated balance sheets. Cost of Revenue Cost of revenue is expensed as incurred, and includes direct labor, material costs, equipment and infrastructure expenses, internal-use software, allocated overhead, and shipping and handling. Material costs include both the disposable costs of the device and amortization of the PCBAs. Each time the PCBA is used in a ZIO Patch, a portion of the cost of the PCBA is recorded as a cost of revenue. Research and Development The Company’s research and development costs are expensed as incurred. Research and development costs include, but are not limited to, payroll and personnel-related expenses, laboratory supplies, consulting costs and overhead charges. Income Taxes The Company uses the asset and liability method to account for income taxes in accordance with the authoritative guidance for income taxes. Under this method, deferred tax assets and liabilities are determined based on future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and tax loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is established when necessary to reduce deferred tax assets to the amount expected to be realized. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company records interest and penalties related to unrecognized tax benefits in income tax expense. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits. Stock-Based Compensation The Company measures its stock-based awards made to employees based on the estimated fair values of the awards as of the grant date. Stock options use the Black-Scholes option-pricing model to estimate fair market value. Stock-based compensation expense is recognized over the requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. For restricted stock, the compensation cost for these awards is based on the closing price of the Company’s common stock on the date of grant, and recognized as compensation expense on a straight-line basis over the requisite service period. The Company recognizes compensation expense related to the Employee Stock Purchase Program (“ESPP”) based on the estimated fair value of the options on the date of grant, net of estimated forfeitures. The Company estimates the grant date fair value, and the resulting stock-based compensation expense, using the Black-Scholes option pricing model for each purchase period. The grant date fair value is expensed on a straight-line basis over the offering period. Net Loss per Common Share Basic net loss per common share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per common share is the same as basic net loss per common share for all periods presented, since the effect of potentially dilutive securities are anti-dilutive. Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current period presentation. These reclassifications had no effect on the Company’s results of operations, net loss or cash flows. Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”), issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). Areas of revenue recognition that will be affected include, but are not limited to, transfer of control, variable consideration, allocation of transfer pricing, licenses, time value of money, contract costs and disclosures. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of Effective Date, which defers the effective date of ASU 2014-09 by one year allowing early adoption as of the original effective date of fiscal years and interim reporting periods beginning after December 15, 2016, at which time companies may adopt the new standard update under the full retrospective method or the modified retrospective method. The deferral results in the new revenue standard being effective for the Company for fiscal years and interim reporting periods beginning after December 15, 2017. In March, April and May 2016, the FASB issued additional updates to the new revenue standard relating to reporting revenue on a gross versus net basis, identifying performance obligations and licensing arrangements, and narrow-scope improvements and practical expedients, respectively. The Company plans on adopting this standard on January 1, 2018 and has not made the decision as to which adoption method it will utilize. The Company’s final determination will depend on the significance of the impact of the new standard on the Company’s financial results. The Company is in the initial stages of its evaluation of the adoption of the new standard on its accounting policies. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements Going Concern— Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern The Company adopted this guidance effective December 31, 2016, and there was no impact on the disclosures to its consolidated financial statements. In July 2015, the FASB issued ASU No. 2015-11, Inventory, Simplifying the Measurement of Inventory. Under ASU 2015-11, the measurement principle for inventory will change from lower of cost or market value to lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The ASU is effective for fiscal years and interim periods within those years beginning after December 15, 2016. The Company does not expect that the adoption of the guidance will have a material effect on its consolidated financial statements. In November 2015, the FASB issued ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. Under ASU 2015-17, deferred tax liabilities and assets will be classified as noncurrent on the balance sheet. Previous guidance required deferred tax liabilities and assets to be separated into current and noncurrent amounts on the balance sheet. The guidance is effective for annual periods beginning after December 15, 2016 and for interim periods within those annual periods. Early adoption is permitted. The Company does not expect that the adoption of the guidance will have a material effect on its consolidated financial statements. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. The Company has not determined the potential effects of this ASU on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires a lessee to recognize assets and liabilities on its consolidated balance sheet for leases with accounting lease terms of more than 12 months. ASU 2016-02 will replace most existing lease accounting guidance in U.S. GAAP when it becomes effective. The new standard states that a lessee will recognize a lease liability for the obligation to make lease payments and a right-of-use asset for the right to use the underlying asset for the lease term. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the consolidated statements of operations. ASU 2016-02 will be effective for our first quarter of fiscal 2020 and requires the modified retrospective method of adoption. Early adoption is permitted. Although we are currently evaluating the effect that ASU 2016-02 will have on our consolidated financial statements and related disclosures, we expect that most of our operating lease commitments will be subject to the new standard and recognized as operating lease liabilities and right-of-use assets upon adoption. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718). This ASU was issued as part of the FASB’s simplification initiative and affects all entities that issue share-based payment awards to their employees. This standard covers accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The ASU will be effective for annual periods ending after December 15, 2016 and interim periods beginning after December 15, 2016 with early adoption permitted. The Company is currently evaluating the impact of adopting this standard on its consolidated financial statements. In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses (Topic 326) In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230) – Classification of Certain Cash Receipts and Cash Payments In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) – Restricted Cash, In January 2017, the FASB issued a new accounting standard update to simplify the measurement of goodwill by eliminating the Step 2 impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The new guidance required an entity to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The new guidance becomes effective for goodwill impairment tests in fiscal years beginning after December 15, 2019, though early adoption is permitted. The Company is currently assessing the impact of this new guidance.

Cash Equivalents and Investment

Cash Equivalents and Investments	12 Months Ended
	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Cash Equivalents and Investments	3. Cash Equivalents and Investments The fair value of securities, not including cash at December 31, 2016 and 2015, were as follows (in thousands): December 31, 2016 Amortized Gross Unrealized Estimated Cost Gains Losses Fair Value Money market funds $ 45,937 $ — $ — $ 45,937 U.S. government securities 16,479 11 — 16,490 Corporate notes 23,947 — (20 ) 23,927 Commercial paper 24,971 — — 24,971 Total available-for-sale securities $ 111,334 $ 11 $ (20 ) $ 111,325 Classified as: Cash equivalents $ 45,937 Short-term investments 54,407 Long-term investments 10,981 Total cash equivalents and investments $ 111,325 December 31, 2015 Amortized Gross Unrealized Estimated Cost Gains Losses Fair Value Money market funds $ 1,254 $ — $ — $ 1,254 Total available-for-sale securities $ 1,254 $ — $ — $ 1,254 Classified as: Cash equivalents $ 1,254 Available-for-sale securities held as of December 31, 2016 had a weighted average days to maturity of 150 days. There have been no material realized gains or realized losses on available-for-sale securities for the periods presented. As the carrying value approximates the fair value for the Company’s cash equivalents, short-term and long-term marketable securities shown in the tables above, the following table summarizes the fair value of the Company’s cash equivalents, short-term and long-term marketable securities classified by maturity as of December 31, 2016 and 2015 (in thousands): December 31, 2016 2015 Due within one year $ 100,344 $ 1,254 Due after one year through three years 10,981 — Total available-for-sale marketable debt securities $ 111,325 $ 1,254

Fair Value Measurements

Fair Value Measurements	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Fair Value Measurements	4. Fair Value Measurements The Company discloses and recognizes the fair value of its assets and liabilities using a hierarchy that prioritizes the inputs to valuation techniques used to measure fair value. Fair value is defined as the price that would be received to sell an asset or paid to transfer a liability (an exit price) in an orderly transaction between market participants at the reporting date. The hierarchy gives the highest priority to valuations based upon unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to valuations based upon unobservable inputs that are significant to the valuation (Level 3 measurements). The guidance establishes three levels of the fair value hierarchy as follows: Level 1 —Inputs are unadjusted quoted prices in active markets for identical assets or liabilities at the measurement date. Level 2 —Inputs (other than quoted market prices included in Level 1) are either directly or indirectly observable for the asset or liability through correlation with market data at the measurement date and for the duration of the instrument’s anticipated life. Level 3 —Inputs reflect management’s best estimate of what market participants would use in pricing the asset or liability at the measurement date. Consideration is given to the risk inherent in the valuation technique and the risk inherent in the inputs to the model. Assets and liabilities measured at fair value are classified in their entirety based on the lowest level of input that is significant to the fair value measurement. The Company’s assessment of the significance of a particular input to the fair value measurement in its entirety requires management to make judgments and consider factors specific to the asset or liability. The corporate notes, commercial paper and government bonds are classified as Level 2 as they were valued based upon quoted market prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active and model-based valuation techniques for which all significant inputs are observable in the market or can be corroborated by observable market data for substantially the full term of the assets. Based on Level 2 inputs and the borrowing rates currently available to the Company for loans with similar terms and maturities, the carrying value of the Company’s debt approximates its fair value. The following table presents the fair value of the Company’s financial assets and liabilities determined using the inputs defined above (amounts in thousands). December 31, 2016 Level 1 Level 2 Level 3 Total Assets Money market funds $ 45,937 $ — $ — $ 45,937 U.S. government securities — 16,490 — 16,490 Corporate notes — 23,927 — 23,927 Commercial paper — 24,971 — 24,971 Total $ 45,937 $ 65,388 $ — $ 111,325 December 31, 2015 Level 1 Level 2 Level 3 Total Assets Money market funds $ 1,254 $ — $ — $ 1,254 Total $ 1,254 $ — $ — $ 1,254 Liabilities Preferred stock warrant liabilities $ — $ — $ 2,949 $ 2,949 Total $ — $ — $ 2,949 $ 2,949 The following table sets forth a summary of the changes in the fair value of the preferred stock warrants which is classified as Level 3 in the fair value hierarchy. There were no transfers into or out of Level 3 during the periods (in thousands): Year Ended December 31, 2016 2015 Beginning balance $ 2,949 $ 2,794 Fair value of preferred stock warrants issued in connection with long-term debt — 44 Exercise of preferred stock warrants (251 ) — Total change in fair value recorded as other expense, net 2,123 111 Reclassification of warrant liability to additional paid-in capital (4,821 ) — Ending balance $ — $ 2,949 The valuation of the preferred stock warrant liabilities is discussed in Note 12.

Balance Sheet Components

Balance Sheet Components	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Balance Sheet Components	5. Balance Sheet Components Inventory and PCBAs Inventory and PCBAs consisted of the following (in thousands): December 31, 2016 2015 Raw materials $ 839 $ 629 Finished goods 3,324 2,147 Total $ 4,163 $ 2,776 December 31, 2016 2015 Reported on the consolidated balance sheet as: Inventory $ 1,390 $ 1,145 Other assets 2,773 1,631 Total $ 4,163 $ 2,776 Amounts reported as other assets are comprised of the PCBA costs that are included in both raw materials and finished goods totals above. Property and Equipment, Net Property and equipment, net consisted of the following (in thousands): December 31, 2016 2015 Laboratory and manufacturing equipment $ 1,509 $ 1,130 Computer equipment and software 736 538 Furniture and fixtures 657 114 Leasehold improvements 502 344 Internal-use software 2,900 993 Total property and equipment, gross 6,304 3,119 Less: accumulated depreciation and amortization (1,651 ) (1,083 ) Total property and equipment, net $ 4,653 $ 2,036 Depreciation and amortization expense for the years ended December 31, 2016, 2015 and 2014 was $568,000, $492,000, and $242,000 respectively. Accrued Liabilities Accrued liabilities consisted of the following (in thousands): December 31, 2016 2015 Accrued vacation $ 1,642 $ 1,250 Accrued payroll and related expenses 6,179 3,838 Accrued professional services fees 636 652 Other 1,708 959 Total accrued liabilities $ 10,165 $ 6,699

Related-Party Transactions

Related-Party Transactions	12 Months Ended
	Dec. 31, 2016
Related Party Transactions [Abstract]
Related-Party Transactions	6 . Related-Party Transactions Kaiser Permanente (“Kaiser”) is a common stock holder of the Company, representing 6.1% ownership of the total outstanding shares of the Company as of December 31, 2016. For the years ended December 31, 2016, 2015, and 2014 the Company recognized revenue of $2.5 million, $1.8 million and $1.4 million, respectively, for transactions with Kaiser. The amounts receivable from transactions with Kaiser were $449,000 and $366,000 as of December 31, 2016 and 2015, respectively. Kaiser additionally performs services related to clinical trials and the Company utilizes Kaiser for employee healthcare. The total expense recorded was $614,000, $597,000 and $193,000 as of December 31, 2016, 2015 and 2014, respectively, and was included in cost of revenues and operating expenses. The amounts outstanding and included in accounts payable and accrued liabilities were $229,000 and $261,000 as of December 31, 2016 and 2015, respectively.

Commitments and Contingencies

Commitments and Contingencies	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Commitments and Contingencies	7. Commitments and Contingencies Lease Arrangements The Company leases office and manufacturing space under non-cancelable operating leases which expire on various dates through 2020. These leases generally contain scheduled rent increases or escalation clauses and renewal options. The Company recognizes rent expense on a straight-line basis over the lease period. The following table summarizes the Company’s future minimum lease payments as of December 31, 2016 (in thousands): Year Ending December 31: 2017 $ 4,678 2018 4,712 2019 4,721 2020 782 Total $ 14,893 The Company’s rent expense was $3.1 million, $1.6 million and $1.3 million for the years ended December 31, 2016, 2015 and 2014, respectively. Legal Proceedings From time to time, the Company may become involved in legal proceedings arising from the ordinary course of its business. Management is currently not aware of any matters that could have a material adverse effect on the financial position, results of operations or cash flows of the Company. Indemnifications In the ordinary course of business, the Company enters into agreements that may include indemnification provisions. Pursuant to such agreements, the Company may indemnify, hold harmless and defend an indemnified party for losses suffered or incurred by the indemnified party. Some of the provisions will limit losses to those arising from third-party actions. In some cases, the indemnification will continue after the termination of the agreement. The maximum potential amount of future payments the Company could be required to make under these provisions is not determinable. The Company has also entered into indemnification agreements with its directors and officers that may require the Company to indemnify its directors and officers against liabilities that may arise by reason of their status or service as directors or officers to the fullest extent permitted by California corporate law. The Company currently has directors’ and officers’ insurance. The Company has never incurred material costs to defend lawsuits or settle claims related to these indemnification provisions, and believes that the estimated fair value of these indemnification obligations is not material and it has not accrued any amounts for these obligations.

Debt

Debt	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Debt	8. Debt Pharmakon Loan Agreement In December 2015, the Company entered into a Loan Agreement with Biopharma Secured Investments III Holdings Cayman LP, or Pharmakon (the “Pharmakon Loan Agreement”). The Pharmakon Loan Agreement provides for up to $55.0 million in term loans split into two tranches as follows: (i) the Tranche A Loans are $30.0 million in term loans, and (ii) the Tranche B Loans are up to $25.0 million in term loans. The Tranche A Loans were drawn on December 4, 2015. The Tranche B Loans were available to be drawn prior to December 4, 2016. No additional draw was made. During the first full eight quarters, payments are interest only and for the first two years 50% of the interest will be “paid in kind.” The Company is subject to a financial covenant related to minimum trailing revenue targets that begins in June 2017, and is tested on a semi-annual basis. The minimum net revenue covenant ranges from $44.7 million for the period ended June 30, 2017 to $102.6 million for the period ended December 31, 2021. The minimum net revenues financial covenant has a 45-day equity cure period following required delivery date of the financial statements. Pursuant to this equity cure provision, the Company may cure a revenue covenant default by raising additional funds from the sale of equity. The loan matures December 2021. The Tranche A Loans bear interest at a fixed rate equal to 9.50% per annum that is due and payable quarterly in arrears. During the first eight calendar quarters, 50% of the interest due and payable is added to the then outstanding principal. The Pharmakon Loan Agreement requires the Company to maintain a minimum consolidated liquidity and minimum net revenue during the term of the loan facility and contains customary affirmative and negative covenants and event of default provisions that could result in the acceleration of the repayment obligations under the loan facility. Upon a change in control of the Company, Pharmakon has the option to demand payment in full of the outstanding loans together with any prepayment premium. The obligations under the Pharmakon Loan Agreement are secured by a security interest in substantially all of the Company’s assets pursuant to the Pharmakon Guaranty and Security Agreement and this security interest is governed by an intercreditor agreement between Pharmakon and Silicon Valley Bank (“SVB”). In December 2015, the Company used the proceeds from the Pharmakon Loan Agreement to repay $4.9 million of bank debt to SVB. The issuance costs and debt discount have been netted against the borrowed funds on the balance sheet. The debt balance, net of debt discount and issuance costs, as of December 31, 2016 and 2015, was $30.8 million and $29.1 million, respectively. Bank Debt Loan and Security Agreement In January 2014, the Company amended its bank debt with SVB by entering into the First Amendment and Default Waiver (“First Amendment”) which amended covenant details. In June 2014, the Company refinanced its debt with SVB by entering into the Second Amendment to the Amended and Restated Loan Security Agreement (“Second Amendment”). Under this amendment the Company borrowed $4.9 million with an additional advance of $5.0 million available. All the borrowings under the Second Amendment were collateralized by all of the Company’s assets, excluding intellectual property. In connection with entering into the Amended Loan Agreement, the Company issued warrants to purchase 20,136 shares of Series D at $7.31 per share that expire June 2024 (See Note 11). In December 2015, the Company used the proceeds from the Pharmakon Loan Agreement to repay $4.9 million of bank debt to SVB and entered into a Second Amended and Restated Loan and Security Agreement with SVB (“SVB Loan Agreement”). Under the SVB Loan Agreement the Company may borrow, repay and reborrow under a revolving credit line, but not in excess of the maximum loan amount of $15.0 million, until December 4, 2018, when all outstanding principal and accrued interest becomes due and payable. Any principal amount outstanding under the SVB revolving credit line will bear interest at a floating rate per annum equal to the rate published by The Wall Street Journal as the “Prime Rate” plus 0.25%. The Company may borrow up to 80% of its eligible accounts receivable, up to the maximum of $15.0 million. In August 2016, the Company obtained a $3.1 million standby letter of credit pursuant to its SVB loan agreement in connection with a new lease for the San Francisco office. As of December 31, 2016 and 2015, the Company was eligible to borrow up to $2.5 million and $2.9 million, respectively, under the SVB revolving credit line. The SVB Loan Agreement requires the Company to maintain a minimum consolidated liquidity and minimum net sales during the term of the loan facility. In addition, the SVB Loan Agreement contains customary affirmative and negative covenants and events of default. The obligations under the SVB Loan Agreement are collaterialized by substantially all assets of the Company and this security interest is governed by an intercreditor agreement between Pharmakon and SVB. California HealthCare Foundation Note In November 2012, the Company entered into a Note Purchase Agreement and Promissory Note with the California HealthCare Foundation (the “CHCF Note”) through which the Company borrowed $1.5 million. The CHCF Note accrues simple interest of 2.0%. The accrued interest and the principal originally matured in November 2016. In partial consideration for the issuance of the CHCF Note, the Company issued warrants to purchase 22,807 shares of the Company’s Series D convertible preferred stock. In June 2015, the Company amended the CHCF Note to extend the maturity date to May 2018. In partial consideration for the amendment, the Company issued 8,552 warrants at $6.58 exercise price per share for shares of the Company’s Series D convertible preferred stock. See Note 12 for further discussion of the warrants. The CHCF note is subordinate to other bank debt. The debt balance, net of debt discount, as of December 31, 2016 and 2015 was $1.5 million and $1.4 million, respectively. Future minimum payments Future minimum payments under the CHCF Note and Pharmakon Loan at December 31, 2016 are as follows (in thousands): Year Ending December 31: 2017 $ 1,549 2018 4,858 2019 3,192 2020 19,169 2021 17,564 46,332 Less: Amount representing interest (13,241 ) Less: Amount representing debt discount and issuance costs (864 ) Present value of minimum payments $ 32,227

Income Taxes

Income Taxes	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Income Taxes	9. Income Taxes The Company operates in the United States for tax reporting purposes. The Company did not record a provision or benefit for income taxes during the years ended December 31, 2016, 2015 and 2014, as it reported losses in each period which are not more likely than not to be realized. Due to the uncertainties surrounding the realization of deferred tax assets through future taxable income, the Company has provided a full valuation allowance and, therefore, no benefit has been recognized for the net operating loss carryforwards and other deferred tax assets. The following table presents a reconciliation of the tax expense computed at the statutory federal rate and the Company’s tax expense for the period presented (in thousands): Year Ended December 31, 2016 2015 2014 Tax at statutory federal rate $ (7,107 ) $ (7,752 ) $ (5,365 ) State taxes, net of federal benefit — — 3 Stock-based compensation 255 251 281 Other 916 (128 ) 166 Tax credits (139 ) (178 ) (168 ) Change in valuation allowance 6,075 7,807 5,083 Provision for income taxes $ — $ — $ — The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands): December 31, 2016 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 38,694 $ 34,714 $ 27,318 Tax credit carryforwards 1,587 1,728 1,388 Allowances and other 4,787 2,024 807 Depreciation and amortization (207 ) 99 357 Total deferred tax assets 44,861 38,565 29,870 Valuation allowance (44,861 ) (38,565 ) (29,870 ) Net deferred tax assets $ — $ — $ — Due to the uncertainties surrounding the realization of deferred tax assets through future taxable income, the Company has provided a full valuation allowance and, therefore, no benefit has been recognized for the net operating loss carryforwards and other deferred tax assets. As of December 31, 2016, the Company had approximately $104.6 million of federal and $58.6 million of state net operating loss carryforwards available to offset future taxable income which expires in varying amounts beginning in 2027 and 2017, respectively. As of December 31, 2016, the Company had tax credit carryforwards of approximately $1.3 million, and $1.2 million available to reduce future taxable income, if any, for both federal and state purposes, respectively. The federal tax credit carryforwards expire beginning in 2027 and the state tax credits can be carried forward indefinitely. The Tax Reform Act of 1986, and similar state provisions, limits the use of net operating loss and tax credit carryforwards in certain situations where equity transactions result in a change of ownership as defined by Internal Revenue Code Section 382. In the event the Company should experience an ownership change, as defined, utilization of its net operating loss carryforwards and tax credits could be limited. The Company has not completed a formal 382 study to analyze prior ownership changes. Previous or future ownership changes may limit the utilization of the Company’s net operating losses. A reconciliation of the Company’s unrecognized tax benefit amount is as follows (in thousands): Year Ended December 31, 2016 2015 2014 Balance at beginning of year $ 570 $ 460 $ 364 Additions for tax positions taken in current year 75 110 96 Decreases in balances related to prior year tax position (29 ) — — Balance at end of year $ 616 $ 570 $ 460 The Company does not anticipate the total amounts of unrecognized tax benefits will significantly increase or decrease in the next 12 months. The Company’s policy is to include interest and penalties related to unrecognized tax benefits within the provision for taxes. Management determined that no accrual for interest or penalties was required as of December 31, 2016 and 2015. All of the Company’s tax years are open to examination by the U.S. federal and state tax authorities.

Stockholders' Equity

Stockholders' Equity	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Stockholders' Equity	10. Stockholders’ Equity Common stock The Company’s amended and restated certificate of incorporation dated October 25, 2016, authorized the Company to issue 100,000,000 shares of common stock with a par value of $0.001 per share and 5,000,000 shares of preferred stock with a par value of $0.001 per share. The holders of common stock are entitled to receive dividends whenever funds and assets are legally available and when declared by the board of directors, subject to the prior rights of holders of all series of convertible preferred stock outstanding. No dividends were declared as of December 31, 2016. The Company had reserved shares of common stock for issuance, on an as-if converted basis, as follows: December 31, 2016 2015 Convertible preferred stock outstanding — 13,343,981 Options issued and outstanding 2,977,218 2,685,913 RSUs issued and unvested 105,529 — Convertible preferred stock warrants — 328,114 Common stock warrants issued 217,245 — Shares available for grant under future stock plans 4,226,068 331,938 7,526,060 16,689,946

Convertible Preferred Stock

Convertible Preferred Stock	12 Months Ended
	Dec. 31, 2016
Temporary Equity Disclosure [Abstract]
Convertible Preferred Stock	11. Convertible Preferred Stock In connection with the completion of the Company’s IPO in October 2016, the Company’s 11,077,505 outstanding shares of convertible preferred stock were converted into 13,375,333 shares of common stock. The table below provides information on the Company’s convertible preferred stock offerings as of December 31, 2015 (in thousands, except shares and original issue price): Shares Original Issue Price Authorized Issued and Outstanding As-if converted to common Liquidation Amount Proceeds Net of Issuance Costs Series A convertible preferred stock $ 5.67 3,415,649 3,390,963 3,390,963 $ 19,236 $ 19,134 Series B convertible preferred Stock $ 16.39 623,254 610,134 1,222,944 10,000 9,855 Series C convertible preferred stock $ 16.39 1,360,582 1,351,423 3,036,448 33,224 21,953 Series D convertible preferred stock $ 7.31 2,627,595 2,327,897 2,327,897 25,516 16,843 Series E convertible preferred stock $ 8.77 3,365,802 3,365,729 3,365,729 29,519 29,311 Total convertible preferred stock 11,392,882 11,046,146 13,343,981 $ 117,495 $ 97,096 The rights, preferences and privileges of the Series A convertible preferred stock (“Series A”), Series B convertible preferred stock (“Series B”), Series C convertible preferred stock (“Series C”), Series D convertible preferred stock (“Series D”) and Series E convertible preferred stock (“Series E”) are as follows: Voting Each share of Series A, Series B, Series C, Series D and Series E has voting rights equal to an equivalent number of shares of common stock into which it is convertible and vote together as one class with the common stock. The holders of Series A and Series C, each voting as a separate class, are entitled to elect two members of the Company’s board of directors, respectively. The holders of Series D, Series E and common stock, each voting as a separate class, are entitled to elect one member of the Company’s board of directors, respectively. Any additional members of the Company’s board of directors may be elected by holders of common stock and preferred stock, voting together as a single class on an as-if converted to common stock basis. Dividends Holders of Series E are entitled to receive dividends, when, as and if declared and unanimously approved by the board of directors, at the dividend rate of $0.71 per share. No distributions shall be made with respect to the Series A, Series B, Series C, Series D or the common stock unless the Series E dividend has been declared, and all such declared dividends have been paid or set aside for payment to the holders of Series E. After the payment or the setting aside of payment of the Series E dividend, the holders of outstanding shares of Series D shall be entitled to receive dividends, when, as and if declared by the board of directors, with unanimous approval, out of any assets at the time legally available therefore, at the dividend rate of $0.59 per share. After the payment or the setting aside of payment of the Series D dividend the holders of outstanding shares of Series B and Series C shall be entitled to receive dividends, when, as and if declared by the board of directors, with unanimous approval, out of any assets at the time legally available therefore, at the dividend rate of $1.29 and $1.29 per share, respectively. After the payment or the setting aside of payment of the Series B and Series C dividends, the holders of Series A shall be entitled to receive dividends, when, as and if declared by the board of directors, with unanimous approval, out of the assets at the time legally available therefore, at the dividend rate of $0.47 per share. No distributions shall be made with respect to the common stock unless the Series A dividend has been declared in accordance with the preferences stated herein and all such declared dividends have been paid or set aside for payment to the holders of Series A. The right to receive dividends on shares of Series A, Series B, Series C, Series D and Series E is not cumulative, and no rights to dividends shall accrue to holders of Series A, Series B, Series C, Series D and Series E by reasons on the fact that dividends on the shares are not declared or paid. No dividends have been declared through December 31, 2016. Liquidation In the event of any liquidation, dissolution or winding up of the Company, either voluntarily or involuntarily, the holders of Series E are entitled to receive, prior and in preference to the holders of Series A, Series B, Series C, Series D and common stock, a per share amount equal to 1.0 times the purchase price plus any declared but unpaid dividends thereon. If upon the liquidation, dissolution or winding up of the Company, the assets of the Company legally available for distribution to the holders of Series E are insufficient to permit the payment to such holders of the full amounts above, then the entire assets of the Company legally available for distribution shall be distributed with equal priority and pro rata among the holders of the Series E in proportion to what they would otherwise be entitled to receive. After the payment or the setting aside of payment of the full Series E liquidation preference and unpaid dividends, the holders of Series D shall be entitled to receive prior and in preference to the holders of Series C, Series B, Series A and common stock, a per share amount equal to 1.5 times the purchase price plus any declared but unpaid dividends thereon. If upon the liquidation, dissolution or winding up of the Company, the assets of the Company legally available for distribution to the holders of Series D are insufficient to permit the payment to such holders of the full amounts above, then the entire assets of the Company legally available for distribution shall be distributed with equal priority and pro rata among the holders of the Series E in proportion to what they would otherwise be entitled to receive. After the payment or setting aside of the full Series E and Series D liquidation preference and unpaid dividends the holders of Series C shall be entitled to receive, pari passu with Series B, prior and in preference to the holders of Series A and common stock, a per share amount equal to 1.5 times and 1.0 times their purchase price plus any declared but unpaid dividends thereon, respectively. If upon the liquidation, dissolution or winding up of the Company, the assets of the Company legally available for distribution to the holders of Series C and Series B are insufficient to permit the payment to such holders of the full amounts above, then the entire assets of the Company legally available for distribution shall be distributed with equal priority and pro rata among the holders of the Series C and Series B in proportion to what they would otherwise be entitled to receive. After the payment or the setting aside of payment of the full Series E, D, B and C liquidation preference and unpaid dividends, Series A stock shall be entitled to receive, prior and in preference to any distribution of any of the assets of the Company to the holders of common stock, an amount per share for each share of Series A held by them equal to 1.0 times the purchase price plus all declared but unpaid dividends thereon, if any, on such share of Series A. If upon the liquidation, dissolution or winding up of the Company, the assets of the Company legally available for distribution to the holders of the preferred stock are insufficient to permit the payment to such holders of the full amounts above, then the entire assets of the Company legally available for distribution shall be distributed with equal priority and pro rata among the holders of the Series A. After the payment or setting aside payment of the full Series E, D, B, C and A liquidation preference and unpaid dividends, the entire remaining assets of the Company legally available for distributions shall be distributed pro rata to holders of common stock. Conversion Each share of preferred stock is convertible, at the option of the holder at any time after the date of issuance of such share, into such number of fully paid and non-assessable shares of common stock determined by dividing the original issue price by the conversion price for such series in effect at the time of conversion. The conversion price for the Series A, Series B, Series C, Series D and Series E is subject to adjustment in accordance with conversion provisions contained in the Company’s certificate of incorporation. The Series A, Series D and Series E convertible preferred stock are convertible into common stock on a one-for-one basis. The Series B and Series C convertible preferred stock are convertible into common stock on a one-for-2.00438849 and one-for-2.24685484 basis, respectively. The conversion price for the preferred stock is subject to anti-dilution provisions. Each share of Series A, Series B, Series C, Series D and Series E is automatically converted into shares of common stock at the conversion price at the time in effect for such share immediately upon the Company’s sale of its common stock in a public offering provided that the offering price is not less than $17.65 per share (as adjusted for recapitalizations, stock combinations, stock dividends, stock splits and the like) and which results in aggregate cash proceeds of not less than $40.0 million before underwriting discounts, commissions, and fees (“Qualified IPO”). The preferred stock will also automatically convert upon the request for such conversion from the holders of at least 63% of the then outstanding shares of preferred stock and holders voting together as a single class on an as-if converted to common stock basis. Classification The Company had classified the convertible preferred stock as mezzanine equity on the consolidated balance sheets as the stock was contingently redeemable. Upon the occurrence of certain change in control events that are outside the Company’s control, including liquidation, sale or transfer of the Company, holders of the convertible preferred stock could cause redemption for cash. The Company had elected not to adjust the carrying value of the convertible preferred stock to the liquidation preferences of such shares because it was uncertain whether or when an event would occur that would obligate the Company to pay the liquidation preferences to the holders of convertible preferred stock. Subsequent adjustments to the carrying values to the liquidation preferences would be made only when it became probable that such a liquidation event would occur.

Preferred Stock Warrant Liabili

Preferred Stock Warrant Liabilities	12 Months Ended
	Dec. 31, 2016
Preferred Stock Warrant Liabilities [Abstract]
Preferred Stock Warrant Liabilities	12. Preferred Stock Warrant Liabilities In connection with a loan agreement that was entered into in November 2009, the Company issued a warrant to purchase 15,865 shares of Series A Preferred Stock at $5.67 per share that expires in November 2019. The fair value of the warrant was determined using the Black Scholes option pricing model and the following assumptions: volatility of 70%, risk free rate of 2.2%, exercise price of $5.67, and an expected life of ten years. The fair value of the warrant, $68,000, was recorded as a debt issuance cost and amortized over the loan draw down period to interest expense. The Company recorded a charge of $182,000, $38,000, and $28,000 related to change in the fair value of the warrants for the years ended December 31, 2016, 2015 and 2014, respectively. Upon the IPO, the Series A preferred stock warrant converted into a common stock warrant was reclassified to additional paid-in-capital in the Company's balance sheet. The warrant was exercised through a cashless exercise on October 26, 2016 resulting in the issuance of a net 12,491 shares of the Company's common stock. In November 2009, in connection with borrowings under a loan agreement, the Company issued warrants to purchase 8,813 shares of Series A Preferred Stock at $5.67 per share that expire November 2019. The fair value of the warrant was determined using the Black Scholes option pricing model and the following assumptions: volatility of 70%, risk free rate of 2.2%, exercise price of $5.67, and an expected life of ten years. The fair value of the warrant, $38,000, was recorded as a debt discount and amortized over the loan repayment period to interest expense. The Company recorded a charge of $101,000, $22,000, and $15,000 related to change in the fair value of the warrants for the years ended December 31, 2016, 2015 and 2014, respectively. Upon the IPO, the Series A preferred stock warrant converted into a common stock warrant and was reclassified to additional paid-in-capital in the Company's balance sheet. The warrant was exercised through a cashless exercise on October 26, 2016 resulting in the issuance of a net 6,939 shares of the Company's common stock. In May 2010, in connection with borrowings under a loan agreement, the Company issued warrants to purchase 1,525 shares of Series B Preferred Stock at $16.39 per share that expire November 2019. The fair value of the warrant was determined using the Black-Scholes option pricing model and the following assumptions: volatility of 60%, risk free rate of 2.8%, exercise price of $16.39, and expected life of 9.5 years. The fair value of the warrant, $19,000, was recorded as a debt discount and amortized over the loan repayment period to interest expense. The Company recorded a charge of $14,000, $5,000 and $4,000 related to change in the fair value of the warrants for the years ended December 31, 2016, 2015 and 2014, respectively. Upon the IPO, the Series A preferred stock warrants converted into common stock warrants and was reclassified to additional paid-in-capital in the Company's balance sheet. The warrant was exercised through a cashless exercise on October 26, 2016 resulting in the issuance of a net 2,119 shares of the Company's common stock. In February 2011, in connection with borrowings under a loan agreement, the Company issued warrants to purchase 11,592 shares of Series B Preferred Stock at $16.39 per share that expire February 2021. The fair value of the warrant was determined using the Black-Scholes option pricing model and the following assumptions: volatility of 60%, risk free rate of 3.4%, exercise price of $16.39, and expected life of 10 years. The fair value of the warrant, $121,000, was recorded as a debt discount and amortized over the loan repayment period to interest expense. The Company recognized a charge of $104,000, $42,000 and $29,000 related to change in the fair value of the warrants for the years ended December 31, 2016, 2015 and 2014, respectively. Upon the IPO, the Series A preferred stock warrants converted into common stock warrants and was reclassified to additional paid-in-capital in the Company's balance sheet. The warrant was exercised through a cashless exercise on October 26, 2016 resulting in the issuance of a net 16,113 shares of the Company's common stock. In November 2012, in connection with borrowings under a convertible note, the Company issued warrants to purchase shares of Series C or New Preferred. The warrants were only exercisable if the Convertible Notes were converted into Series C or New Preferred. The warrants’ exercise price is $0.01 per share and they have a seven year term. On March 27, 2013 the Company closed the Series D financing. The warrants were converted into warrants to purchase 207,177 shares of Series D convertible preferred stock. The Company recognized a charge of $1,199,000, income of $42,000, and a charge of $178,000 related to change in the fair value of the warrants for the years ended December 31, 2016, 2015 and 2014, respectively. Upon the IPO when the Series A preferred stock warrants converted into common stock warrants and were reclassified to additional paid-in-capital in the Company's balance sheet. As a result, the warrants are no longer subject to fair value remeasurement. In November 2012, in connection with borrowings under the CHCF Note (Note 8), the Company issued warrants to purchase shares of Series C or shares in the next equity financing with proceeds of at least $500,000. The warrants are for the number of shares equal to $150,000 divided by the price of Series C or the next equity financing and expire at the earlier of November 2022 or a liquidation event. To fair value the warrants at the date of issue and at December 31, 2012, the Company assumed Series C shares, which resulted in warrants to purchase 9,152 shares. The fair value of the warrants was determined using the Black-Scholes option pricing model and the following assumptions: volatility of 60%, risk free rate of 1.6%, exercise price of $16.39 and expected life of ten years. The fair value of the warrants, $153,000, was recorded as a debt discount and is being amortized over the loan repayment period to interest expense. On March 27, 2013 the Company closed the Series D financing. The warrants were converted into warrants to purchase 22,807 shares of Series D stock. The Company recognized a charge of $50,000, $14,000, and $24,000 related to change in the fair value of the warrants for the years ended December 31, 2016, 2015 and 2014, respectively. The warrants were exercised on October 3, 2016. In April 2013, in connection with borrowings under a loan agreement, the Company issued warrants to purchase 18,474 shares of Series D Preferred Stock at $7.31 per share that expire April 2023. The fair value of the warrant was determined by using an option pricing model prepared by a third-party based on an allocation of the company’s aggregate value to the outstanding equity instruments, applying a 22% discount to the warrant value for lack of marketability. The fair value of the warrant, $72,000, was recorded as a debt discount and is being amortized over the loan repayment period to interest expense, net. The Company recognized a charge of $217,000, $12,000 and $19,000 related to change in the fair value of the warrants for the year ended December 31, 2016, 2015 and 2014, respectively. The warrants were converted into warrants to purchase common stock upon the completion of the IPO in 2016, and were reclassified to additional paid-in-capital in the Company's balance sheet. The warrant was exercised through a cashless exercise on October 26, 2016 resulting in the issuance of a net 13,414 shares of the Company's common stock. In June 2014, in connection with borrowings under the Second Amendment (Note 8), the Company issued warrants to purchase 20,136 shares of Series D Preferred Stock at $7.31 per share that expire June 2024. The fair value of the warrant was determined by using an option pricing model prepared by a third-party based on an allocation of the Company’s aggregate value to the outstanding equity instruments, applying a 30% discount to the warrant value for lack of marketability. The fair value of the warrant, $98,000, was recorded as a debt discount and is being amortized over the loan repayment period to interest expense. The Company recognized a charge of $237,000, a charge of $14,000, and income of $4,000 related to change in the fair value of the warrants for the years ended December 31, 2016, 2015 and 2014, respectively. The warrants were converted into warrants to purchase common stock upon the completion of the IPO in 2016, and were reclassified to additional paid-in-capital in the Company's balance sheet. The warrant for 10,068 shares was exercised through a cashless exercise on October 26, 2016 resulting in the issuance of a net 7,310 shares of the Company's common stock, and the warrant for 10,068 shares remains outstanding as of December 31, 2016. In June 2015, in connection with the First Amendment of the CHCF Note, the Company issued warrants to purchase 8,552 shares of Series D Preferred Stock at $6.58 per share that expire at the earlier of November 2022 or a liquidation event. The fair value of the warrant was determined by using an option pricing model prepared by a third-party based on an allocation of the Company’s aggregate value to the outstanding equity instruments, applying discount rates of 13-27% to the warrant value for lack of marketability based on the anticipated holding periods to potential liquidity events utilized in the probability-weighted expected return model (“PWERM”). The fair value of the warrant, $44,000, was recorded as debt discount and is being amortized over the loan repayment period to interest expense. The Company recognized a charge of $19,000 and $6,000 related to change in the fair value of the warrants for the years ended December 31, 2016 and, 2015, respectively. The warrants were exercised on October 3, 2016.

Stock Incentive Plans

Stock Incentive Plans	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock Incentive Plans	13. Stock Incentive Plans 2006 Plan In October 2006, the Company adopted the 2006 Equity Incentive Plan, as amended, (the “2006 Plan”). The Plan provides for the granting of stock options to employees and non-employees of the Company. Options granted under the Plan may be either incentive stock options or nonqualified stock options. Incentive stock options (“ISO”) may be granted only to employees (including officers and directors who are also employees). Nonqualified stock options (“NSO”) may be granted to employees and non-employees. The board of directors has the authority to determine to whom options will be granted, the number of options, the term and the exercise price. Options under the Plan may be granted for periods of up to ten years and at prices no less than 85% of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided, however, that (i) the exercise price of an ISO and NSO shall not be less than 100% and 85% of the estimated fair value of the shares on the date of grant, respectively, and (ii) the exercise price of an ISO and NSO granted to a 10% stockholder shall not be less than 110% of the estimated fair value of the shares on the date of grant. In general, options become exercisable at a rate of 25% after the first anniversary of the grant and then monthly vesting for an additional three years from date of grant. The term for options is no longer than five years for ISOs for which the grantee owns greater than 10% of the voting power of all classes of stock and no longer than ten years for all other options. The Company issues new shares upon the exercise of options. 2016 Plan In October 2016, the Company adopted the 2016 Equity Incentive Plan, (the “2016 Plan”). The 2016 Plan was subsequently approved by the Company’s stockholders and became effective on October 19, 2016, immediately before the effective date of the IPO. Following the effectiveness of the 2016 Plan, no additional options will be granted under the 2006 Plan. An aggregate of 3,865,000 additional shares are reserved for issuance under the 2016 Plan. In addition, to the extent that any awards outstanding or subject to vesting restrictions under the 2006 Plan are subsequently forfeited or terminated for any reason before being exercised or settled, the shares of common stock reserved for issuance pursuant to such awards as of the closing of the IPO will become available for issuance under the 2016 Plan. The remaining shares available for grant under the 2006 Plan became available for issuance under the 2016 Plan upon the closing of the IPO. On the first day of each year beginning with 2017, the 2016 Plan authorizes an annual increase of the least of 3,865,000 shares, 5% of outstanding shares on the last day of the immediately preceding fiscal year or an amount as determined by the Company's Board of Directors. As of December 31, 2016, 3,743,037 shares were available for future issuance under the 2016 Plan. Pursuant to the 2016 Plan, stock options, restricted shares, stock units, including restricted stock units and stock appreciation rights may be granted to employees, consultants, and outside directors of the Company. Options granted may be either ISOs or NSOs. Stock options are governed by stock option agreements between the Company and recipients of stock options. ISOs and NSOs may be granted under the 2016 Plan at an exercise price of not less than 100% of the fair market value of the common stock on the date of grant, determined by the Compensation Committee of the Board of Directors. Options become exercisable and expire as determined by the Compensation Committee, provided that the term of ISOs may not exceed ten years from the date of grant. Employee Stock Purchase Program (“ESPP”) In October 2016, the Company’s Board of Directors and stockholders approved the Employee Stock Purchase Plan (the “ESPP”). Under the ESPP, the Company initially reserved 483,031 shares of common stock for issuance as of its effective date of October 19, 2016. On the first day of each calendar year, beginning in 2017, the number of shares in the reserve will increase by the least of 966,062 shares, 1.5% of the shares of the Company’s common stock outstanding on the last day of the immediately preceding fiscal year the number of shares of stock as determined by the Company’s Board of Directors. The ESPP allows eligible employees to purchase shares of the Company’s common stock at a discount through payroll deductions of up to 15% of their eligible compensation, subject to any plan limitations. The ESPP provides for twelve-month offering periods which each contain two six-month purchase periods. At the end of each purchase period, employees are able to purchase shares at 85% of the lower of the fair market value of the Company’s common stock on the first trading day of the offering period or on the last day of the purchase period. As of December 31, 2016, no shares of common stock have been issued to employees participating in the ESPP and 483,031 shares were available for issuance under the ESPP. The Company used the following assumptions to estimate the fair value of the ESPP offered for the year ended December 31, 2016: expected term of .61 – 1.12 years, volatility of 53.21% - 57.69%, risk-free interest rate of 0.52% - 0.68% and expected dividend yield of zero. Option Plan Activity A summary of share-based awards available for grant is as follows: Shares for Grant Balance at December 31, 2013 382,071 Additional options authorized 356,979 Options granted (429,474 ) Options forfeited 38,238 Balance at December 31, 2014 347,814 Additional options authorized 781,954 Options granted (915,080 ) Options forfeited 117,250 Balance at December 31, 2015 331,938 Additional options authorized 3,865,000 Options granted (466,914 ) Options forfeited 13,013 Balance at December 31, 2016 3,743,037 The following table summarizes stock option activity under the 2006 and 2016 Plans, including grants to nonemployees: Options Outstanding Options Outstanding Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in Balance at December 31, 2013 1,620,129 $ 3.59 8.20 Options granted 429,474 $ 3.86 Options exercised (38,982 ) $ 1.30 Options forfeited (38,238 ) $ 3.34 Balance at December 31, 2014 1,972,383 $ 3.70 7.86 $ 4,191 Options granted 915,080 $ 3.98 Options exercised (84,300 ) $ 3.71 Options forfeited (117,250 ) $ 3.94 Balance at December 31, 2015 2,685,913 $ 4.81 7.63 $ 11,589 Options granted 361,385 $ 15.65 Options exercised (57,067 ) $ 2.33 Options forfeited (13,013 ) $ 6.92 Balance at December 31, 2016 2,977,218 $ 6.16 6.93 $ 70,979 Options exercisable – December 31, 2016 1,940,798 $ 4.35 6.25 $ 49,775 Options vested and expected to vest – December 31, 2016 2,912,854 $ 6.06 7.06 $ 69,746 The aggregate intrinsic values of options outstanding, exercisable, vested and expected to vest were calculated as the difference between the exercise price of the options and the closing price of the Company’s common stock. During the years ended December 31, 2016, 2015 and 2014, the Company granted options with a weighted-average grant date fair value of $8.76, $4.08 and $2.20 per share, respectively. The aggregate intrinsic value of options exercised was $654,000, $237,000 and $96,000 for the years ended December 31, 2016, 2015 and 2014, respectively. The total estimated grant date fair value of options vested during the period was $1.8 million, $1.1 million and $869,000, for the years ended December 31, 2016, 2015 and 2014, respectively. The fair value of nonvested restricted stock units (“RSUs”) is based on our closing stock price on the date of grant. A summary for the year ended December 31, 2016, is as follows: Shares Underlying RSUs Weighted Average Grant Date Fair Value Weighted Remaining Vesting Period (in years) Aggregate Intrinsic Value (in Nonvested as of December 31, 2015 — $ — Granted 105,529 27.39 Vested and released — — Forfeited — — Nonvested as of December 31, 2016 105,529 $ 27.39 2.12 $ 3,166

Stock-Based Compensation

Stock-Based Compensation	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Stock-Based Compensation	14. Stock-Based Compensation Employee Stock-Based Compensation The Company estimates the fair value of stock options using the Black-Scholes option valuation model. The fair value of employee stock options is being amortized on a straight-line basis over the requisite service period of the awards. The fair value of employee stock options was estimated using the weighted average assumptions below. Each of these inputs is subjective and its determination generally requires significant judgment. Year Ended December 31 2016 2015 2014 Expected term (in years) 6.1 6.1 6.1 Expected volatility 60.0 % 60.0 % 60.0 % Risk-free interest rate 1.42 % 1.76 % 2.08 % Dividend yield 0.0 % 0.0 % 0.0 % Fair Value of Common Stock — Prior to the completion of the Company’s IPO, the fair value of the shares of the Company’s common stock underlying the stock options had historically been determined by the Company’s board of directors. Because there had been no public market for the Company’s common stock, its board of directors determined the fair value of the Company’s common stock at the time of grant of the option by considering a number of objective and subjective factors, including valuations of comparable companies, sales of the Company’s convertible preferred stock, the Company’s operating and financial performance, the lack of liquidity of the Company’s capital stock, and the general and industry-specific economic outlooks. For stock options granted after the completion of the IPO, the Company’s Board of Directors determined the fair value of each share of underlying common stock based on the closing price of the Company’s common stock as reported on the date of grant. Expected Term —The expected term represents the period that the share-based awards are expected to be outstanding. As the Company has very limited historical information to develop reasonable expectations about future exercise patterns and post-vesting employment termination behavior for its stock-option grants the Company has elected to use the “simplified method” as prescribed by authoritative guidance to compute expected term. Expected Volatility —Since the Company does not have trading history for its common stock, the expected volatility was estimated based on the average volatility for comparable publicly traded companies over a period equal to the expected term of the stock option grants. When selecting comparable publicly traded companies in a similar industry on which it has based its expected stock price volatility, the Company selected companies with comparable characteristics to it, including enterprise value, risk profiles, position within the industry, and with historical share price information sufficient to meet the expected life of the stock-based awards. The Company will continue to apply this process until a sufficient amount of historical information regarding the volatility of its own stock price becomes available. Risk-Free Interest Rate —The risk-free interest rate is based on the U.S. Treasury yield curve in effect on the date of grant for zero coupon U.S. Treasury notes with maturities approximately equal to expected term of the option award. Expected Dividend Yield —The Company has never paid dividends on its common stock and has no plans to pay dividends on its common stock. Therefore, the Company used an expected dividend yield of zero. In addition to the assumptions used in the Black-Scholes option-pricing model, the Company also estimates a forfeiture rate to calculate the stock-based compensation for the Company’s equity awards. The Company will continue to use judgment in evaluating the expected volatility, expected terms and forfeiture rates utilized for the Company’s stock-based compensation calculations on a prospective basis. The following table summarizes the total stock-based compensation expense for options, RSUs and ESPP included in the consolidated statements of operations and comprehensive loss for all periods presented (in thousands): Year Ended December 31 2016 2015 2014 Cost of revenue $ 17 $ 17 $ 15 Research and development 203 165 80 Selling, general and administrative 1,651 1,228 733 Total stock-based compensation expense $ 1,871 $ 1,410 $ 828 As of December 31, 2016, there was total unamortized compensation costs of $5.1 million, net of estimated forfeitures, related to unvested stock options which the Company expects to recognize over a period of approximately 2.9 years, $2.8 million, net of estimated forfeitures, related to unrecognized RSU expense, which the Company expects to recognize over a period of 2.1 years, and $1.9 million unrecognized ESPP expense, which the company will recognize over .92 years. Non-Employee Stock-Based Compensation Stock based compensation expense related to stock options granted to nonemployees is recognized as the stock options are earned. The measurement of stock based compensation for non-employees is subject to periodic adjustment as the underlying equity instruments vest, and the related compensation expense is based on the estimated fair value of the equity instruments using the Black Scholes option pricing model. The Company believes that the estimated fair value of the stock options is more readily measurable than the fair value of the services received. Such expense was not material for the years ended December 31, 2016, 2015 and 2014.

Net Loss Per Common Share

Net Loss Per Common Share	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Net Loss Per Common Share	15. Net Loss Per Common Share As the Company had net losses for the years ended December 31, 2016, 2015 and 2014, all potential common shares were determined to be anti-dilutive. The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2016, 2015 and 2014 (in thousands, except share and per share data): Year Ended December 31, 2016 2015 2014 Numerator: Net loss $ (20,903 ) $ (22,799 ) $ (15,832 ) Denominator: Weighted-average shares used to compute net loss per common share, basic and diluted 5,285,847 1,376,106 1,314,294 Net loss per common share, basic and diluted $ (3.95 ) $ (16.57 ) $ (12.05 ) The following outstanding shares of potentially dilutive securities have been excluded from diluted net loss per common share for the years ended December 31, 2016, 2015 and 2014, because their inclusion would be anti-dilutive: Year Ended December 31, 2016 2015 Convertible preferred stock on an as-if converted basis — 13,343,981 Options to purchase common stock 2,977,218 2,685,913 RSUs issued and unvested 105,529 — Warrants to purchase convertible preferred stock on an as-if converted basis — 328,114 Warrants to purchase common stock 217,245 — Total 3,299,992 16,358,008

Selected Quarterly Financial Da

Selected Quarterly Financial Data (Unaudited)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Selected Quarterly Financial Data (Unaudited)	16. Selected Quarterly Financial Data (unaudited) The following table presents selected unaudited financial data for each of the eight quarters in the two-year period ended December 31, 2016. The Company believes this information reflects all recurring adjustments necessary to fairly state this information when read in conjunction with the Company's financial statements and the related notes. Net loss per common share, basic and diluted, for the four quarters of each fiscal year may not sum to the total for the fiscal year because of the different number of shares outstanding during each period. The results of operations for any quarter are not necessarily indicative of the results to be expected for any future period (in thousands of dollars, except for share and per share data): Quarter Ended March 31 June 30 September 30 December 31 2016: Total revenues $ 12,854 $ 15,734 $ 16,780 $ 18,704 Gross profit 8,195 10,578 11,498 12,918 Net loss (6,126 ) (4,436 ) (4,075 ) (6,266 ) Net loss per common share, basic and diluted $ (4.34 ) $ (3.12 ) $ (2.80 ) $ (0.37 ) 2015: Total revenues $ 7,055 $ 8,887 $ 9,344 $ 10,854 Gross profit 3,882 5,269 5,596 6,693 Net loss (4,392 ) (4,959 ) (5,746 ) (7,702 ) Net loss per common share, basic and diluted $ (3.31 ) $ (3.66 ) $ (4.07 ) $ (5.46 )

Summary of Significant Accoun25

Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation The accompanying consolidated financial statements are consolidated for the year ended December 31, 2016 and include the accounts of iRhythm Technologies, Inc. and its wholly-owned subsidiary, iRhythm Technologies Ltd., established in March 2016. All intercompany accounts and transactions have been eliminated. All accompanying financial statements and disclosures for the years ended December 31, 2015 and December 31, 2014 include only the accounts of iRhythm Te chnologies, Inc. The financial statements of iRhythm Technologies Ltd. use the U.S. dollar as the functional currency
Use of Estimates	Use of Estimates The preparation of the consolidated financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. On an ongoing basis, management evaluates its estimates, including those related to revenue recognition, contractual allowances for revenue, allowance for doubtful accounts, the useful lives of property and equipment, the recoverability of long-lived assets including the estimated usage of the printed circuit board assemblies (“PCBAs”), the valuation of deferred tax assets, the fair value of the Company’s preferred and common stock and stock-based compensation. The Company bases these estimates on historical and anticipated results, trends, and various other assumptions that the Company believes are reasonable under the circumstances, including assumptions as to future events. Actual results may differ from those estimates.
Fair Value of Financial Instruments	Fair Value of Financial Instruments The carrying amounts of certain of the Company’s financial instruments, which includes cash equivalents, accounts receivable, prepaid expenses, accounts payable and accrued liabilities, approximate fair value due to their short maturities.
Cash and Cash Equivalents	Cash and Cash Equivalents Cash equivalents consist of short-term, highly liquid investments with original maturities of three months or less from the date of purchase. Cash equivalents consist primarily of amounts invested in money market funds.
Investments	Investments Short-term investments consist of debt securities classified as available-for-sale and have maturities greater than 90 days, but less than 365 days from the date of acquisition. Long-term investments have maturities greater than 365 days as of the balance sheet date. All investments are carried at fair value based upon quoted market prices. Unrealized gains and losses on available-for-sale securities are excluded from earnings and are reported as a component of accumulated other comprehensive loss. The cost of available-for-sale securities sold is based on the specific-identification method. Realized gains and losses are included in earnings, and are derived for specific-identification method for determining the costs of investments sold.
Restricted Cash	Restricted Cash Restricted cash consists of certificates of deposit held with a financial institution as security deposits for building leases, and is included in current assets on the Company’s consolidated balance sheets.
Accounts Receivable, Allowance for Doubtful Accounts and Contractual Allowance	Accounts Receivable, Allowance for Doubtful Accounts and Contractual Allowance Accounts receivable consists of amounts due to the Company from institutions, government payors and commercial insurance payors as a result of the Company’s normal business activities. Accounts receivable is reported on the balance sheet net of an estimated allowance for doubtful accounts and contractual allowance. The Company establishes an allowance for doubtful accounts for estimated uncollectible receivables based on historical collections, review of specific outstanding claims, consideration of relevant qualitative factors and an established allowance percentage by aging category. The Company writes off amounts against the allowance for doubtful accounts when they are deemed to be uncollectible. Increases and decreases in the allowance for doubtful accounts are included as a component of selling, general and administrative expenses. The Company establishes a contractual allowance, which is a reduction in revenue, for estimated uncollectible amounts from Centers for Medicare & Medicaid Services (“CMS”), and contracted third-party commercial payors. The following table presents the changes in the allowance for doubtful accounts: December 31, December 2016 2015 Balance, beginning of year $ 1,125 $ 470 Add: provision for doubtful accounts 1,960 1,177 Less: write-offs, net of recoveries and other adjustments (1,293 ) (522 ) Balance, end of year $ 1,792 $ 1,125 The following table presents the changes in the contractual allowance: December 31, December 31, 2016 2015 Balance, beginning of year $ 338 $ 91 Add: contractual allowances 2,726 380 Less: write-offs, net of recoveries and other adjustments (724 ) (133 ) Balance, end of year $ 2,340 $ 338 Management reviews and updates its estimates for the allowance for doubtful accounts and the contractual allowance periodically to reflect its experience regarding historical collections. If management were to make different judgments or utilize different estimates in the allowance for doubtful accounts and the contractual allowance, differences in the amount of reported selling, general and administrative expenses and revenue could result, respectively.
Concentration of Credit Risk	Credit Risk Financial instruments that potentially subject the Company to a concentration of credit risk consist primarily of cash and cash equivalents, investments and accounts receivable. Cash and cash equivalents and investments are deposited with one financial institution in the United States of America. At times, such deposits may be in excess of federally insured limits. Cash equivalents are invested in highly rated money market funds. The Company invests in a variety of financial instruments, such as, but not limited to, United States Government securities, corporate notes, commercial paper and, by policy, limits the amount of credit exposure with any one financial institution or commercial issuer. The Company has not experienced any material losses on its deposits of cash and cash equivalents or investments. Concentrations of credit risk with respect to accounts receivable are limited due to the large number of customers comprising the Company’s customer base and their dispersion across many geographies. The Company does not require collateral. The Company records an allowance for doubtful accounts when it becomes probable that a receivable will not be collected. Government agencies, including CMS and the Veterans Administration, accounted for 40%, 41% and 30% of the Company’s revenue for the years ended December 31, 2016, 2015 and 2014, respectively. Accounts receivable related to federal government agencies accounted for 27% and 30% at December 31, 2016 and 2015, respectively.
Concentration of Supply Risk	Supply Risk The Company relies on single suppliers for the supply of its reusable printed circuit board assemblies, disposable housings, instruments and other materials used to manufacture the ZIO Patch and the adhesive that binds the ZIO Patch to a patient’s body. These components and materials are critical, and there would be a considerable delay in finding alternative sources of supply.
Inventory	Inventory Inventory is stated at the lower of cost or market, cost being determined on a standard cost basis for material costs and on actual cost basis for labor and overhead, which approximates actual cost on a first in, first out (“FIFO”) basis, and market being determined as the lower of replacement cost or net realizable value. The Company records write-downs of inventory that is obsolete or in excess of anticipated demand or market value based on consideration of product lifecycle stage, technology trends, product development plans and assumptions about future demand and market conditions. Actual demand may differ from forecasted demand, and such differences may have a material effect on recorded inventory values. Inventory write-downs are charged to cost of revenue and establish a new cost basis for the inventory.
Property and Equipment	Property and Equipment Property and equipment are stated at cost less accumulated depreciation and amortization. Depreciation and amortization is computed using the straight-line method over the estimated useful lives of the assets, ranging from three to five years. Leasehold improvements are amortized over the shorter of the lease term or the estimated useful lives of the assets. Maintenance and repairs are charged to expense as incurred, and improvements and betterments are capitalized.
Internal-Use Software	Internal-Use Software The Company capitalizes costs related to internal-use software during the application development stage. Costs related to planning and post implementation activities are expensed as incurred. Capitalized internal-use software is amortized on a straight-line basis over the estimated useful life, which is up to five years. The Company evaluates the useful lives of these assets on an annual basis, and tests for impairment whenever events or changes in circumstances occur that could impact the recoverability of these assets. Capitalized internal-use software costs are classified as a component of property and equipment.
Goodwill	Goodwill Goodwill represents the excess of the purchase price paid over the fair value of tangible and identifiable intangible net assets acquired in business combinations. Goodwill is tested for impairment on an annual basis and at any other time if events occur or circumstances indicate that the carrying amount of goodwill may not be recoverable. Such events or circumstances may include significant adverse changes in the general business climate, among other things. The impairment test is performed by determining the enterprise fair value of the Company, which is primarily based on the Company’s public market capitalization. If the Company’s carrying value, as a one reporting unit entity, is less than its fair value, then the fair value is allocated to all of its assets and liabilities (including any unrecognized intangible assets) as if the fair value was the purchase price to acquire the Company. The excess of the fair value over the amounts assigned to the Company’s assets and liabilities is the implied fair value of the goodwill. If the carrying amount of goodwill exceeds the implied fair value of that goodwill, an impairment loss is recognized in an amount equal to that excess. The Company performs its annual evaluation of goodwill during the fourth quarter of each fiscal year. The Company did not record any charges related to goodwill impairment in any of the periods presented in these consolidated financial statements.
Impairment of Long-Lived Assets	Impairment of Long-Lived Assets The Company annually reviews long-lived assets for impairment or whenever events or changes in circumstances indicate that the carrying amount of an asset may not be recoverable. Recoverability is measured by comparison of the carrying amount to the future net cash flows which the assets are expected to generate. If such assets are considered to be impaired, the impairment to be recognized is measured as the amount by which the carrying amount of the assets exceeds the projected discounted future net cash flows arising from the asset. To date, there have been no such impairments of long-lived assets.
Other Assets	Other Assets Included in the other assets are printed circuit board assemblies, or PCBAs, totaling $2.8 million and $1.6 million as of December 31, 2016 and 2015, respectively. The Company uses a PCBA in each wearable device and it is used numerous times. Each time the PCBA is used in a wearable device, a portion of the cost of the PCBA is recorded as a cost of revenue. The Company has based its estimates of how many times a PCBA can be used on testing in research and development, loss rates, product obsolescence, and the amount of time it takes the device to go through the manufacturing, shipping, customer shelf and patient wear time and upload process. The Company periodically evaluates the use estimate.
Deferred Offering Costs	Deferred Offering Costs Deferred offering costs, which consisted primarily of legal, accounting, printer and filing fees related to the IPO, were capitalized. As of December 31, 2015, the Company capitalized $0.3 million of deferred offering costs in other long-term assets on the balance sheet. Deferred offering costs of $3.7 million were offset against IPO proceeds upon the completion of the offering in October 2016.
Preferred Stock Warrant Liabilities	Preferred Stock Warrant Liabilities The Company measured freestanding warrants to purchase shares of its convertible preferred stock at fair value, and recorded the related amounts as liabilities, because the shares underlying the warrants could obligate the Company to transfer assets to the holders at a future date under certain circumstances such as a deemed liquidation event. The fair value of the preferred stock warrants was remeasured at each balance sheet date, and any change in fair value was included in earnings. Such charges were included in other expense, net in the consolidated statements of operations and comprehensive loss. In connection with the Company’s IPO, the Company remeasured the liability at the time of the IPO, and then reclassified the redeemable convertible preferred stock warrant liability to additional paid-in capital, as these warrants converted to common stock warrants. As of December 31, 2016, there were no convertible preferred stock warrants outstanding, and 217,245 common stock warrants were outstanding.
Comprehensive Loss	Comprehensive Loss Comprehensive loss represents all changes in stockholders’ equity (deficit) except those resulting from and distributions to stockholders. The Company’s unrealized gains and losses on available-for-sale securities represent the only component of other comprehensive loss that are excluded from the reported net loss and that are presented in the consolidated statements of comprehensive loss.
Revenue Recognition	Revenue Recognition The Company’s devices, cardiac rhythm monitors, have a wear period for up to 14 days for the ZIO Patch or 30 days for the ZIO Event Card. The Company’s services, consisting of the delivery of reports containing analysis of data captured by the physical device to the prescribing physician, are generally billable at the start of the wear period or when reports are issued to physicians, depending on the service provided. For the ZIO Event Card, the Company recognizes revenue on a straight-line basis over the applicable wear period, as the event monitoring results are delivered to physicians. For the ZIO Service, the Company recognizes the revenue at the time that a report is delivered to a physician. For all services performed, the Company considers whether or not the following revenue recognition criteria are met: persuasive evidence of an arrangement exists and delivery has occurred or services have been rendered. For services performed for customers the Company invoices directly, additional revenue recognition criteria include that the price is fixed and determinable and collectability is reasonably assured; for customers in which the Company submits claims to third-party commercial and governmental payors for reimbursement, the Company recognizes revenue only when a reasonable estimate of reimbursement can be made. The assessment of whether a reasonable estimate of reimbursement can be made requires significant judgment by management. Where management’s judgment indicates a reasonable estimate of reimbursement can be made, revenue is recognized upon delivery of the patient report for the ZIO Service and straight-line for the ZIO Event Card. To date, the Company has not been able to estimate revenue for third-party payors for which it does not have a contracted rate, and therefore, revenue has been recognized on the earlier of notice or cash receipt. Some patients have out-of-pocket costs for amounts not covered by their insurance carrier, and the Company may bill the patient directly for these amounts in the form of co-payments and co-insurance in accordance with their insurance carrier and health plans. Some payors may not cover the Company’s service as ordered by the prescribing physician under their reimbursement policies. In the absence of contracted reimbursement coverage or the ability to reasonably estimate reimbursement, the Company recognizes revenue only upon the earlier of notification or when payment is received. The Company recognizes revenue related to billings for CMS and commercial payors on an accrual basis, net of contractual adjustments, when a reasonable estimate of reimbursement can be made. These contractual adjustments represent the difference between the list price (the billing rate) and the reimbursement rate for each payor. Upon ultimate collection from CMS and commercial payors, the amount is compared to the previous estimates and the contractual allowance is adjusted accordingly. Until a contract has been negotiated with a commercial payor, the Company’s services may or may not be covered by these entities’ existing reimbursement policies. In addition, patients do not enter into direct agreements with the Company that commit them to pay any portion of the cost of the service in the event that their insurance declines to reimburse the Company. In the absence of an agreement with the patient or other clearly enforceable legal right to demand payment from the patient, the related revenue is recognized only upon the earlier of notification of payment or when payment is received. Revenue recognized when cash or notification of coverage was received was $11.2 million, $3.5 million, and $0.6 million for the years ended December 31, 2016, 2015 and 2014, respectively. Revenue recognized on an accrual basis was $52.9 million, $32.6 million, and $21.2 million for the years ended December 31, 2016, 2015 and 2014, respectively. Certain of the Company’s customers pay the Company directly for the ZIO Service upon shipment of devices. Such advance payments are recorded as deferred revenue on the consolidated balance sheets.
Cost of Revenue	Cost of Revenue Cost of revenue is expensed as incurred, and includes direct labor, material costs, equipment and infrastructure expenses, internal-use software, allocated overhead, and shipping and handling. Material costs include both the disposable costs of the device and amortization of the PCBAs. Each time the PCBA is used in a ZIO Patch, a portion of the cost of the PCBA is recorded as a cost of revenue.
Research and Development	Research and Development The Company’s research and development costs are expensed as incurred. Research and development costs include, but are not limited to, payroll and personnel-related expenses, laboratory supplies, consulting costs and overhead charges.
Income Taxes	Income Taxes The Company uses the asset and liability method to account for income taxes in accordance with the authoritative guidance for income taxes. Under this method, deferred tax assets and liabilities are determined based on future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases, and tax loss and credit carryforwards. Deferred tax assets and liabilities are measured using enacted tax rates applied to taxable income in the years in which those temporary differences are expected to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in income in the period that includes the enactment date. A valuation allowance is established when necessary to reduce deferred tax assets to the amount expected to be realized. The Company recognizes the effect of income tax positions only if those positions are more likely than not of being sustained. Recognized income tax positions are measured at the largest amount that is greater than 50% likely of being realized. Changes in recognition or measurement are reflected in the period in which the change in judgment occurs. The Company records interest and penalties related to unrecognized tax benefits in income tax expense. To date, there have been no interest or penalties charged in relation to the unrecognized tax benefits.
Stock-Based Compensation	Stock-Based Compensation The Company measures its stock-based awards made to employees based on the estimated fair values of the awards as of the grant date. Stock options use the Black-Scholes option-pricing model to estimate fair market value. Stock-based compensation expense is recognized over the requisite service period using the straight-line method and is based on the value of the portion of stock-based payment awards that is ultimately expected to vest. As such, the Company’s stock-based compensation is reduced for the estimated forfeitures at the date of grant and revised, if necessary, in subsequent periods if actual forfeitures differ from those estimates. For restricted stock, the compensation cost for these awards is based on the closing price of the Company’s common stock on the date of grant, and recognized as compensation expense on a straight-line basis over the requisite service period. The Company recognizes compensation expense related to the Employee Stock Purchase Program (“ESPP”) based on the estimated fair value of the options on the date of grant, net of estimated forfeitures. The Company estimates the grant date fair value, and the resulting stock-based compensation expense, using the Black-Scholes option pricing model for each purchase period. The grant date fair value is expensed on a straight-line basis over the offering period.
Net Loss per Common Share	Net Loss per Common Share Basic net loss per common share is calculated by dividing the net loss by the weighted average number of shares of common stock outstanding during the period, without consideration of potentially dilutive securities. Diluted net loss per common share is the same as basic net loss per common share for all periods presented, since the effect of potentially dilutive securities are anti-dilutive.
Reclassification of Prior Year Presentation	Reclassification of Prior Year Presentation Certain prior year amounts have been reclassified for consistency with the current period presentation. These reclassifications had no effect on the Company’s results of operations, net loss or cash flows.
Recent Accounting Pronouncements	Recent Accounting Pronouncements In May 2014, the Financial Accounting Standards Board (“FASB”), issued ASU No. 2014-09, Revenue from Contracts with Customers (Topic 606). Areas of revenue recognition that will be affected include, but are not limited to, transfer of control, variable consideration, allocation of transfer pricing, licenses, time value of money, contract costs and disclosures. In August 2015, the FASB issued ASU No. 2015-14, Revenue from Contracts with Customers (Topic 606): Deferral of Effective Date, which defers the effective date of ASU 2014-09 by one year allowing early adoption as of the original effective date of fiscal years and interim reporting periods beginning after December 15, 2016, at which time companies may adopt the new standard update under the full retrospective method or the modified retrospective method. The deferral results in the new revenue standard being effective for the Company for fiscal years and interim reporting periods beginning after December 15, 2017. In March, April and May 2016, the FASB issued additional updates to the new revenue standard relating to reporting revenue on a gross versus net basis, identifying performance obligations and licensing arrangements, and narrow-scope improvements and practical expedients, respectively. The Company plans on adopting this standard on January 1, 2018 and has not made the decision as to which adoption method it will utilize. The Company’s final determination will depend on the significance of the impact of the new standard on the Company’s financial results. The Company is in the initial stages of its evaluation of the adoption of the new standard on its accounting policies. In August 2014, the FASB issued ASU No. 2014-15, Presentation of Financial Statements Going Concern— Disclosure of Uncertainties about an Entity’s Ability to Continue as a Going Concern The Company adopted this guidance effective December 31, 2016, and there was no impact on the disclosures to its consolidated financial statements. In July 2015, the FASB issued ASU No. 2015-11, Inventory, Simplifying the Measurement of Inventory. Under ASU 2015-11, the measurement principle for inventory will change from lower of cost or market value to lower of cost and net realizable value. Net realizable value is the estimated selling prices in the ordinary course of business, less reasonably predictable costs of completion, disposal and transportation. The ASU is effective for fiscal years and interim periods within those years beginning after December 15, 2016. The Company does not expect that the adoption of the guidance will have a material effect on its consolidated financial statements. In November 2015, the FASB issued ASU No. 2015-17, Income Taxes (Topic 740): Balance Sheet Classification of Deferred Taxes. Under ASU 2015-17, deferred tax liabilities and assets will be classified as noncurrent on the balance sheet. Previous guidance required deferred tax liabilities and assets to be separated into current and noncurrent amounts on the balance sheet. The guidance is effective for annual periods beginning after December 15, 2016 and for interim periods within those annual periods. Early adoption is permitted. The Company does not expect that the adoption of the guidance will have a material effect on its consolidated financial statements. In January 2016, the FASB issued ASU No. 2016-01, Recognition and Measurement of Financial Assets and Financial Liabilities, which addresses certain aspects of recognition, measurement, presentation and disclosure of financial instruments. ASU 2016-01 is effective for annual periods, and interim periods within those annual periods, beginning after December 15, 2017. The Company has not determined the potential effects of this ASU on its consolidated financial statements. In February 2016, the FASB issued ASU No. 2016-02, Leases (Topic 842), which requires a lessee to recognize assets and liabilities on its consolidated balance sheet for leases with accounting lease terms of more than 12 months. ASU 2016-02 will replace most existing lease accounting guidance in U.S. GAAP when it becomes effective. The new standard states that a lessee will recognize a lease liability for the obligation to make lease payments and a right-of-use asset for the right to use the underlying asset for the lease term. Leases will be classified as either finance or operating, with classification affecting the pattern of expense recognition in the consolidated statements of operations. ASU 2016-02 will be effective for our first quarter of fiscal 2020 and requires the modified retrospective method of adoption. Early adoption is permitted. Although we are currently evaluating the effect that ASU 2016-02 will have on our consolidated financial statements and related disclosures, we expect that most of our operating lease commitments will be subject to the new standard and recognized as operating lease liabilities and right-of-use assets upon adoption. In March 2016, the FASB issued ASU No. 2016-09, Compensation—Stock Compensation (Topic 718). This ASU was issued as part of the FASB’s simplification initiative and affects all entities that issue share-based payment awards to their employees. This standard covers accounting for income taxes, forfeitures, and statutory tax withholding requirements, as well as classification in the statement of cash flows. The ASU will be effective for annual periods ending after December 15, 2016 and interim periods beginning after December 15, 2016 with early adoption permitted. The Company is currently evaluating the impact of adopting this standard on its consolidated financial statements. In June 2016, the Financial Accounting Standards Board (“FASB”) issued Accounting Standards Update (“ASU”) No. 2016-13, Financial Instruments – Credit Losses (Topic 326) In August 2016, the FASB issued ASU No. 2016-15, Statement of Cash Flows (Topic 230) – Classification of Certain Cash Receipts and Cash Payments In November 2016, the FASB issued ASU No. 2016-18, Statement of Cash Flows (Topic 230) – Restricted Cash, In January 2017, the FASB issued a new accounting standard update to simplify the measurement of goodwill by eliminating the Step 2 impairment test. Step 2 measures a goodwill impairment loss by comparing the implied fair value of a reporting unit’s goodwill with the carrying amount of that goodwill. The new guidance required an entity to compare the fair value of a reporting unit with its carrying amount and recognize an impairment charge for the amount by which the carrying amount exceeds the reporting unit’s fair value. Additionally, an entity should consider income tax effects from any tax deductible goodwill on the carrying amount of the reporting unit when measuring the goodwill impairment loss, if applicable. The new guidance becomes effective for goodwill impairment tests in fiscal years beginning after December 15, 2019, though early adoption is permitted. The Company is currently assessing the impact of this new guidance.

Summary of Significant Accoun26

Summary of Significant Accounting Policies (Tables)	12 Months Ended
	Dec. 31, 2016
Accounting Policies [Abstract]
Schedule of Changes in Allowance for Doubtful Accounts	The following table presents the changes in the allowance for doubtful accounts: December 31, December 2016 2015 Balance, beginning of year $ 1,125 $ 470 Add: provision for doubtful accounts 1,960 1,177 Less: write-offs, net of recoveries and other adjustments (1,293 ) (522 ) Balance, end of year $ 1,792 $ 1,125
Schedule of Changes in Contractual Allowance	The following table presents the changes in the contractual allowance: December 31, December 31, 2016 2015 Balance, beginning of year $ 338 $ 91 Add: contractual allowances 2,726 380 Less: write-offs, net of recoveries and other adjustments (724 ) (133 ) Balance, end of year $ 2,340 $ 338

Cash Equivalents and Investme27

Cash Equivalents and Investments (Tables)	12 Months Ended
	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Schedule of Fair Value of Securities, not Including Cash	The fair value of securities, not including cash at December 31, 2016 and 2015, were as follows (in thousands): December 31, 2016 Amortized Gross Unrealized Estimated Cost Gains Losses Fair Value Money market funds $ 45,937 $ — $ — $ 45,937 U.S. government securities 16,479 11 — 16,490 Corporate notes 23,947 — (20 ) 23,927 Commercial paper 24,971 — — 24,971 Total available-for-sale securities $ 111,334 $ 11 $ (20 ) $ 111,325 Classified as: Cash equivalents $ 45,937 Short-term investments 54,407 Long-term investments 10,981 Total cash equivalents and investments $ 111,325 December 31, 2015 Amortized Gross Unrealized Estimated Cost Gains Losses Fair Value Money market funds $ 1,254 $ — $ — $ 1,254 Total available-for-sale securities $ 1,254 $ — $ — $ 1,254 Classified as: Cash equivalents $ 1,254
Schedule of Fair Value of Short-term and Long-term Marketable Securities Classified by Maturity	As the carrying value approximates the fair value for the Company’s cash equivalents, short-term and long-term marketable securities shown in the tables above, the following table summarizes the fair value of the Company’s cash equivalents, short-term and long-term marketable securities classified by maturity as of December 31, 2016 and 2015 (in thousands): December 31, 2016 2015 Due within one year $ 100,344 $ 1,254 Due after one year through three years 10,981 — Total available-for-sale marketable debt securities $ 111,325 $ 1,254

Fair Value Measurements (Tables

Fair Value Measurements (Tables)	12 Months Ended
	Dec. 31, 2016
Fair Value Disclosures [Abstract]
Schedule of Fair Value of Company's Financial Assets and Liabilities	The following table presents the fair value of the Company’s financial assets and liabilities determined using the inputs defined above (amounts in thousands). December 31, 2016 Level 1 Level 2 Level 3 Total Assets Money market funds $ 45,937 $ — $ — $ 45,937 U.S. government securities — 16,490 — 16,490 Corporate notes — 23,927 — 23,927 Commercial paper — 24,971 — 24,971 Total $ 45,937 $ 65,388 $ — $ 111,325 December 31, 2015 Level 1 Level 2 Level 3 Total Assets Money market funds $ 1,254 $ — $ — $ 1,254 Total $ 1,254 $ — $ — $ 1,254 Liabilities Preferred stock warrant liabilities $ — $ — $ 2,949 $ 2,949 Total $ — $ — $ 2,949 $ 2,949
Summary of Changes in Fair Value of Preferred Stock Warrants Classified as Level 3	The following table sets forth a summary of the changes in the fair value of the preferred stock warrants which is classified as Level 3 in the fair value hierarchy. Year Ended December 31, 2016 2015 Beginning balance $ 2,949 $ 2,794 Fair value of preferred stock warrants issued in connection with long-term debt — 44 Exercise of preferred stock warrants (251 ) — Total change in fair value recorded as other expense, net 2,123 111 Reclassification of warrant liability to additional paid-in capital (4,821 ) — Ending balance $ — $ 2,949

Balance Sheet Components (Table

Balance Sheet Components (Tables)	12 Months Ended
	Dec. 31, 2016
Organization Consolidation And Presentation Of Financial Statements [Abstract]
Components of Inventory and PCBAs	Inventory and PCBAs consisted of the following (in thousands): December 31, 2016 2015 Raw materials $ 839 $ 629 Finished goods 3,324 2,147 Total $ 4,163 $ 2,776 December 31, 2016 2015 Reported on the consolidated balance sheet as: Inventory $ 1,390 $ 1,145 Other assets 2,773 1,631 Total $ 4,163 $ 2,776
Components of Property and Equipment, Net	Property and equipment, net consisted of the following (in thousands): December 31, 2016 2015 Laboratory and manufacturing equipment $ 1,509 $ 1,130 Computer equipment and software 736 538 Furniture and fixtures 657 114 Leasehold improvements 502 344 Internal-use software 2,900 993 Total property and equipment, gross 6,304 3,119 Less: accumulated depreciation and amortization (1,651 ) (1,083 ) Total property and equipment, net $ 4,653 $ 2,036
Components of Accrued Liabilities	Accrued liabilities consisted of the following (in thousands): December 31, 2016 2015 Accrued vacation $ 1,642 $ 1,250 Accrued payroll and related expenses 6,179 3,838 Accrued professional services fees 636 652 Other 1,708 959 Total accrued liabilities $ 10,165 $ 6,699

Commitments and Contingencies (

Commitments and Contingencies (Tables)	12 Months Ended
	Dec. 31, 2016
Commitments And Contingencies Disclosure [Abstract]
Schedule of Future Minimum Lease Payments Under Non-cancelable Operating Leases	The following table summarizes the Company’s future minimum lease payments as of December 31, 2016 (in thousands): Year Ending December 31: 2017 $ 4,678 2018 4,712 2019 4,721 2020 782 Total $ 14,893

Debt (Tables)

Debt (Tables)	12 Months Ended
	Dec. 31, 2016
Debt Disclosure [Abstract]
Schedule of Future Minimum Payments under CHCF Note and Pharmakon Loan	Future minimum payments under the CHCF Note and Pharmakon Loan at December 31, 2016 are as follows (in thousands): Year Ending December 31: 2017 $ 1,549 2018 4,858 2019 3,192 2020 19,169 2021 17,564 46,332 Less: Amount representing interest (13,241 ) Less: Amount representing debt discount and issuance costs (864 ) Present value of minimum payments $ 32,227

Income Taxes (Tables)

Income Taxes (Tables)	12 Months Ended
	Dec. 31, 2016
Income Tax Disclosure [Abstract]
Reconciliation of Tax Expense Computed at Statutory Federal Rate and Company's Tax Expense	The following table presents a reconciliation of the tax expense computed at the statutory federal rate and the Company’s tax expense for the period presented (in thousands): Year Ended December 31, 2016 2015 2014 Tax at statutory federal rate $ (7,107 ) $ (7,752 ) $ (5,365 ) State taxes, net of federal benefit — — 3 Stock-based compensation 255 251 281 Other 916 (128 ) 166 Tax credits (139 ) (178 ) (168 ) Change in valuation allowance 6,075 7,807 5,083 Provision for income taxes $ — $ — $ —
Tax Effects of Temporary Differences and Carryforwards of Deferred Tax Assets	The tax effects of temporary differences and carryforwards that give rise to significant portions of the deferred tax assets are as follows (in thousands): December 31, 2016 2015 2014 Deferred tax assets: Net operating loss carryforwards $ 38,694 $ 34,714 $ 27,318 Tax credit carryforwards 1,587 1,728 1,388 Allowances and other 4,787 2,024 807 Depreciation and amortization (207 ) 99 357 Total deferred tax assets 44,861 38,565 29,870 Valuation allowance (44,861 ) (38,565 ) (29,870 ) Net deferred tax assets $ — $ — $ —
Reconciliation of Unrecognized Tax Benefit	A reconciliation of the Company’s unrecognized tax benefit amount is as follows (in thousands): Year Ended December 31, 2016 2015 2014 Balance at beginning of year $ 570 $ 460 $ 364 Additions for tax positions taken in current year 75 110 96 Decreases in balances related to prior year tax position (29 ) — — Balance at end of year $ 616 $ 570 $ 460

Stockholders' Equity (Tables)

Stockholders' Equity (Tables)	12 Months Ended
	Dec. 31, 2016
Equity [Abstract]
Schedule Of Common Stock Shares Reserved For Future Issuance	The Company had reserved shares of common stock for issuance, on an as-if converted basis, as follows: December 31, 2016 2015 Convertible preferred stock outstanding — 13,343,981 Options issued and outstanding 2,977,218 2,685,913 RSUs issued and unvested 105,529 — Convertible preferred stock warrants — 328,114 Common stock warrants issued 217,245 — Shares available for grant under future stock plans 4,226,068 331,938 7,526,060 16,689,946

Convertible Preferred Stock (Ta

Convertible Preferred Stock (Tables)	12 Months Ended
	Dec. 31, 2016
Temporary Equity Disclosure [Abstract]
Summary of Convertible Preferred Stock Offerings	The table below provides information on the Company’s convertible preferred stock offerings as of December 31, 2015 (in thousands, except shares and original issue price): Shares Original Issue Price Authorized Issued and Outstanding As-if converted to common Liquidation Amount Proceeds Net of Issuance Costs Series A convertible preferred stock $ 5.67 3,415,649 3,390,963 3,390,963 $ 19,236 $ 19,134 Series B convertible preferred Stock $ 16.39 623,254 610,134 1,222,944 10,000 9,855 Series C convertible preferred stock $ 16.39 1,360,582 1,351,423 3,036,448 33,224 21,953 Series D convertible preferred stock $ 7.31 2,627,595 2,327,897 2,327,897 25,516 16,843 Series E convertible preferred stock $ 8.77 3,365,802 3,365,729 3,365,729 29,519 29,311 Total convertible preferred stock 11,392,882 11,046,146 13,343,981 $ 117,495 $ 97,096

Stock Incentive Plans (Tables)

Stock Incentive Plans (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Summary of Share-based Awards Available for Grant	A summary of share-based awards available for grant is as follows: Shares for Grant Balance at December 31, 2013 382,071 Additional options authorized 356,979 Options granted (429,474 ) Options forfeited 38,238 Balance at December 31, 2014 347,814 Additional options authorized 781,954 Options granted (915,080 ) Options forfeited 117,250 Balance at December 31, 2015 331,938 Additional options authorized 3,865,000 Options granted (466,914 ) Options forfeited 13,013 Balance at December 31, 2016 3,743,037
Summary of Stock Option Activity Under 2006 and 2016 Plans, Including Grants To Nonemployees	The following table summarizes stock option activity under the 2006 and 2016 Plans, including grants to nonemployees: Options Outstanding Options Outstanding Weighted- Average Exercise Price Per Share Weighted- Average Remaining Contractual Life (years) Aggregate Intrinsic Value (in Balance at December 31, 2013 1,620,129 $ 3.59 8.20 Options granted 429,474 $ 3.86 Options exercised (38,982 ) $ 1.30 Options forfeited (38,238 ) $ 3.34 Balance at December 31, 2014 1,972,383 $ 3.70 7.86 $ 4,191 Options granted 915,080 $ 3.98 Options exercised (84,300 ) $ 3.71 Options forfeited (117,250 ) $ 3.94 Balance at December 31, 2015 2,685,913 $ 4.81 7.63 $ 11,589 Options granted 361,385 $ 15.65 Options exercised (57,067 ) $ 2.33 Options forfeited (13,013 ) $ 6.92 Balance at December 31, 2016 2,977,218 $ 6.16 6.93 $ 70,979 Options exercisable – December 31, 2016 1,940,798 $ 4.35 6.25 $ 49,775 Options vested and expected to vest – December 31, 2016 2,912,854 $ 6.06 7.06 $ 69,746
Summary of Nonvested Restricted Stock Units ("RSUs")	The fair value of nonvested restricted stock units (“RSUs”) is based on our closing stock price on the date of grant. A summary for the year ended December 31, 2016, is as follows: Shares Underlying RSUs Weighted Average Grant Date Fair Value Weighted Remaining Vesting Period (in years) Aggregate Intrinsic Value (in Nonvested as of December 31, 2015 — $ — Granted 105,529 27.39 Vested and released — — Forfeited — — Nonvested as of December 31, 2016 105,529 $ 27.39 2.12 $ 3,166

Stock-Based Compensation (Table

Stock-Based Compensation (Tables)	12 Months Ended
	Dec. 31, 2016
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Schedule of Fair Value of Employee Stock Options Estimated Using Weighted Average Assumptions	The fair value of employee stock options was estimated using the weighted average assumptions below. Each of these inputs is subjective and its determination generally requires significant judgment. Year Ended December 31 2016 2015 2014 Expected term (in years) 6.1 6.1 6.1 Expected volatility 60.0 % 60.0 % 60.0 % Risk-free interest rate 1.42 % 1.76 % 2.08 % Dividend yield 0.0 % 0.0 % 0.0 %
Summary of Total Stock-Based Compensation Expense for Options, RSUs and ESPP Included in Consolidated Statements of Operations and Comprehensive Loss	The following table summarizes the total stock-based compensation expense for options, RSUs and ESPP included in the consolidated statements of operations and comprehensive loss for all periods presented (in thousands): Year Ended December 31 2016 2015 2014 Cost of revenue $ 17 $ 17 $ 15 Research and development 203 165 80 Selling, general and administrative 1,651 1,228 733 Total stock-based compensation expense $ 1,871 $ 1,410 $ 828

Net Loss Per Common Share (Tabl

Net Loss Per Common Share (Tables)	12 Months Ended
	Dec. 31, 2016
Earnings Per Share [Abstract]
Computation of Basic and Diluted Net Loss per Share	The following table sets forth the computation of the basic and diluted net loss per share during the years ended December 31, 2016, 2015 and 2014 (in thousands, except share and per share data): Year Ended December 31, 2016 2015 2014 Numerator: Net loss $ (20,903 ) $ (22,799 ) $ (15,832 ) Denominator: Weighted-average shares used to compute net loss per common share, basic and diluted 5,285,847 1,376,106 1,314,294 Net loss per common share, basic and diluted $ (3.95 ) $ (16.57 ) $ (12.05 )
Schedule of Anti-dilutive Securities Excluded from Diluted Net Loss per Common Share	The following outstanding shares of potentially dilutive securities have been excluded from diluted net loss per common share for the years ended December 31, 2016, 2015 and 2014, because their inclusion would be anti-dilutive: Year Ended December 31, 2016 2015 Convertible preferred stock on an as-if converted basis — 13,343,981 Options to purchase common stock 2,977,218 2,685,913 RSUs issued and unvested 105,529 — Warrants to purchase convertible preferred stock on an as-if converted basis — 328,114 Warrants to purchase common stock 217,245 — Total 3,299,992 16,358,008

Selected Quarterly Financial 38

Selected Quarterly Financial Data (Unaudited) (Tables)	12 Months Ended
	Dec. 31, 2016
Quarterly Financial Information Disclosure [Abstract]
Schedule of Quarterly Financial Information	The following table presents selected unaudited financial data for each of the eight quarters in the two-year period ended December 31, 2016. The Company believes this information reflects all recurring adjustments necessary to fairly state this information when read in conjunction with the Company's financial statements and the related notes. Net loss per common share, basic and diluted, for the four quarters of each fiscal year may not sum to the total for the fiscal year because of the different number of shares outstanding during each period. The results of operations for any quarter are not necessarily indicative of the results to be expected for any future period (in thousands of dollars, except for share and per share data): Quarter Ended March 31 June 30 September 30 December 31 2016: Total revenues $ 12,854 $ 15,734 $ 16,780 $ 18,704 Gross profit 8,195 10,578 11,498 12,918 Net loss (6,126 ) (4,436 ) (4,075 ) (6,266 ) Net loss per common share, basic and diluted $ (4.34 ) $ (3.12 ) $ (2.80 ) $ (0.37 ) 2015: Total revenues $ 7,055 $ 8,887 $ 9,344 $ 10,854 Gross profit 3,882 5,269 5,596 6,693 Net loss (4,392 ) (4,959 ) (5,746 ) (7,702 ) Net loss per common share, basic and diluted $ (3.31 ) $ (3.66 ) $ (4.07 ) $ (5.46 )

Organization and Description 39

Organization and Description of Business - Additional Information (Details) $ in Thousands	Oct. 31, 2016USD ($)shares	Oct. 19, 2016USD ($)shares	Oct. 05, 2016	Dec. 31, 2016USD ($)	Dec. 31, 2015shares
Class Of Stock [Line Items]
Reverse stock split description				On October 4, 2016, the Company’s board of directors approved an amendment to the Company’s amended and restated certificate of incorporation to effect a reverse split of the Company’s issued and outstanding common stock at a 1-for- 5.882698 ratio, which was effected on October 5, 2016.
Common stock, reverse stock split ratio			5.882698
Proceeds from stock issuance, net of underwriting discounts and commissions				$ 114,436
Number of shares converted into common stock | shares					13,343,981
Carrying value of convertible preferred stock converted into common stock				$ 97,553
Initial Public Offering
Class Of Stock [Line Items]
Common stock issued | shares		7,238,235
Initial public offering closing date		Oct. 25, 2016
Proceeds from stock issuance, net of underwriting discounts and commissions		$ 110,700
Underwriting discounts and commissions		8,600
Other expenses		$ 3,700
Initial Public Offering | Redeemable Convertible Preferred Stock
Class Of Stock [Line Items]
Number of shares converted into common stock | shares	13,375,333
Carrying value of convertible preferred stock converted into common stock	$ 97,600

Summary of Significant Accoun40

Summary of Significant Accounting Policies - Schedule of Changes in Allowance for Doubtful Accounts (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Balance, beginning of year	$ 1,125	$ 470
Add: provision for doubtful accounts	1,960	1,177
Less: write-offs, net of recoveries and other adjustments	(1,293)	(522)
Balance, end of year	$ 1,792	$ 1,125

Summary of Significant Accoun41

Summary of Significant Accounting Policies - Schedule of Changes in Contractual Allowance (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Receivables [Abstract]
Balance, beginning of year	$ 338	$ 91
Add: contractual allowances	2,726	380
Less: write-offs, net of recoveries and other adjustments	(724)	(133)
Balance, end of year	$ 2,340	$ 338

Summary of Significant Accoun42

Summary of Significant Accounting Policies - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Oct. 31, 2016
Summary Of Significant Accounting Policies [Line Items]
Impairment long-lived assets	$ 0
Deferred offering costs		$ 300,000		$ 3,700,000
Income tax position likely of being realized upon ultimate settlement	greater than 50%
Unrecognized tax benefits, income tax interest or penalties charge	$ 0
ZIO Event Card
Summary Of Significant Accounting Policies [Line Items]
Equipment wear period	30 days
Convertible Preferred Stock
Summary Of Significant Accounting Policies [Line Items]
Warrants outstanding	0
Common Stock
Summary Of Significant Accounting Policies [Line Items]
Warrants outstanding	217,245
Internal-Use Software
Summary Of Significant Accounting Policies [Line Items]
Estimated useful life	5 years
Printed Circuit Board Assemblies
Summary Of Significant Accounting Policies [Line Items]
Total other assets	$ 2,800,000	$ 1,600,000
Minimum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	3 years
Maximum
Summary Of Significant Accounting Policies [Line Items]
Property and equipment, estimated useful life	5 years
Maximum | ZIO Patch
Summary Of Significant Accounting Policies [Line Items]
Equipment wear period	14 days
Revenue | Customer Concentration Risk | Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk	40.00%	41.00%	30.00%
Accounts Receivable | Accounts Receivable Concentration Risk | Federal Government Agencies
Summary Of Significant Accounting Policies [Line Items]
Concentration of credit risk	27.00%	30.00%
Revenue Recognized When Cash Received
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized	$ 11,200,000	$ 3,500,000	$ 600,000
Revenue Recognized on Accrual Basis
Summary Of Significant Accounting Policies [Line Items]
Revenue recognized	$ 52,900,000	$ 32,600,000	$ 21,200,000

Cash Equivalents and Investme43

Cash Equivalents and Investments - Schedule of Fair Value of Securities, not Including Cash (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Cash And Cash Equivalents [Line Items]
Amortized Cost	$ 111,334	$ 1,254
Gross Unrealized Gains	11
Gross Unrealized Losses	(20)
Estimated Fair Value	111,325	1,254
Cash equivalents	45,937	1,254
Short-term investments	54,407
Long-term investments	10,981
Total cash equivalents and investments	111,325
Money Market Funds
Cash And Cash Equivalents [Line Items]
Amortized Cost	45,937	1,254
Estimated Fair Value	45,937	$ 1,254
U.S. Government Securities
Cash And Cash Equivalents [Line Items]
Amortized Cost	16,479
Gross Unrealized Gains	11
Estimated Fair Value	16,490
Commercial Paper
Cash And Cash Equivalents [Line Items]
Amortized Cost	24,971
Estimated Fair Value	24,971
Corporate Notes
Cash And Cash Equivalents [Line Items]
Amortized Cost	23,947
Gross Unrealized Losses	(20)
Estimated Fair Value	$ 23,927

Cash Equivalents and Investme44

Cash Equivalents and Investments - Additional Information (Details)	12 Months Ended
	Dec. 31, 2016
Cash And Cash Equivalents [Abstract]
Available-for-sale securities, weighted average days to maturity	150 days

Cash Equivalents and Investme45

Cash Equivalents and Investments - Schedule of Fair Value of Short-term and Long-term Marketable Securities Classified by Maturity (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Marketable Securities [Abstract]
Due within one year	$ 100,344	$ 1,254
Due after one year through three years	10,981
Total available-for-sale marketable debt securities	$ 111,325	$ 1,254

Fair Value Measurements - Sched

Fair Value Measurements - Schedule of Fair Value of Company's Financial Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Assets
Total financial assets	$ 111,325	$ 1,254
Liabilities
Total financial liabilities		2,949
Preferred Stock Warrant Liabilities
Liabilities
Total financial liabilities		2,949
Money Market Funds
Assets
Total financial assets	45,937	1,254
U.S. Government Securities
Assets
Total financial assets	16,490
Corporate Notes
Assets
Total financial assets	23,927
Commercial Paper
Assets
Total financial assets	24,971
Level 1
Assets
Total financial assets	45,937	1,254
Level 1 | Money Market Funds
Assets
Total financial assets	45,937	1,254
Level 2
Assets
Total financial assets	65,388
Level 2 | U.S. Government Securities
Assets
Total financial assets	16,490
Level 2 | Corporate Notes
Assets
Total financial assets	23,927
Level 2 | Commercial Paper
Assets
Total financial assets	$ 24,971
Level 3
Liabilities
Total financial liabilities		2,949
Level 3 | Preferred Stock Warrant Liabilities
Liabilities
Total financial liabilities		$ 2,949

Fair Value Measurements - Addit

Fair Value Measurements - Additional Information (Details)	12 Months Ended
	Dec. 31, 2016USD ($)
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Abstract]
Fair value measurement, liability transfers into level 3, amount	$ 0
Fair value measurement, liability transfers out of level 3, amount	$ 0

Fair Value Measurements - Summa

Fair Value Measurements - Summary of Changes in Fair Value of Preferred Stock Warrants Classified as Level 3 (Details) - Level 3 - Preferred Stock Warrant Liabilities - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items]
Beginning balance	$ 2,949	$ 2,794
Fair value of preferred stock warrants issued in connection with long-term debt		44
Exercise of preferred stock warrants	(251)
Total change in fair value recorded as other expense, net	2,123	111
Reclassification of warrant liability to additional paid-in capital	$ (4,821)
Ending balance		$ 2,949

Balance Sheet Components - Comp

Balance Sheet Components - Components of Inventory and PCBAs (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
Total inventory and printed circuit board assemblies	$ 4,163	$ 2,776
Inventory	1,390	1,145
Other assets	3,052	2,145
PCBA
Inventory [Line Items]
Other assets	2,773	1,631
Raw Materials
Inventory [Line Items]
Total inventory and printed circuit board assemblies	839	629
Finished Goods
Inventory [Line Items]
Total inventory and printed circuit board assemblies	$ 3,324	$ 2,147

Balance Sheet Components - Co50

Balance Sheet Components - Components of Property and Equipment, Net (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 6,304	$ 3,119
Less: accumulated depreciation and amortization	(1,651)	(1,083)
Total property and equipment, net	4,653	2,036
Laboratory and Manufacturing Equipment
Property Plant And Equipment [Line Items]
Total property and equipment, gross	1,509	1,130
Computer Equipment and Software
Property Plant And Equipment [Line Items]
Total property and equipment, gross	736	538
Furniture and Fixtures
Property Plant And Equipment [Line Items]
Total property and equipment, gross	657	114
Leasehold Improvements
Property Plant And Equipment [Line Items]
Total property and equipment, gross	502	344
Internal-Use Software
Property Plant And Equipment [Line Items]
Total property and equipment, gross	$ 2,900	$ 993

Balance Sheet Components - Addi

Balance Sheet Components - Additional Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Property Plant And Equipment [Abstract]
Depreciation and amortization expense	$ 568	$ 492	$ 242

Balance Sheet Components - Co52

Balance Sheet Components - Components of Accrued Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015
Payables And Accruals [Abstract]
Accrued vacation	$ 1,642	$ 1,250
Accrued payroll and related expenses	6,179	3,838
Accrued professional services fees	636	652
Other	1,708	959
Total accrued liabilities	$ 10,165	$ 6,699

Related-Party Transactions - Ad

Related-Party Transactions - Additional Information (Details) - Kaiser - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Related Party Transaction [Line Items]
Revenue recognized	$ 2,500,000	$ 1,800,000	$ 1,400,000
Amounts receivable from transaction	449,000	366,000
Additional service related expenses	614,000	597,000	$ 193,000
Accounts payable and accrued liabilities	$ 229,000	$ 261,000
Convertible Preferred Stock
Related Party Transaction [Line Items]
Convertible preferred stock, ownership percentage	6.10%

Commitments and Contingencies -

Commitments and Contingencies - Future Minimum Lease Payments Under Non-cancelable Operating Leases (Details) $ in Thousands	Dec. 31, 2016USD ($)
Operating Leases Future Minimum Payments Due [Abstract]
2,017	$ 4,678
2,018	4,712
2,019	4,721
2,020	782
Total	$ 14,893

Commitments and Contingencies55

Commitments and Contingencies - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments And Contingencies Disclosure [Abstract]
Rent Expense	$ 3.1	$ 1.6	$ 1.3

Debt - Additional Information (

Debt - Additional Information (Details)

1 Months Ended

12 Months Ended

Jun. 30, 2017USD ($)

Dec. 31, 2015USD ($)Tranche

Jun. 30, 2014USD ($)$ / sharesshares

Nov. 30, 2012USD ($)$ / sharesshares

Dec. 31, 2021USD ($)

Dec. 31, 2016USD ($)

Dec. 31, 2015USD ($)

Dec. 31, 2014USD ($)$ / shares

Dec. 01, 2016USD ($)

Aug. 31, 2016USD ($)

Dec. 04, 2015USD ($)

Jun. 30, 2015$ / sharesshares

Debt Instrument [Line Items]

Repayment of bank debt

$ 4,905,000

$ 4,500,000

Debt balance

$ 46,332,000

Proceeds from long-term debt, net of issuance costs

29,018,000

$ 4,905,000

CHCF Note

Debt Instrument [Line Items]

Debt balance

$ 1,400,000

$ 1,500,000

1,400,000

Proceeds from long-term debt, net of issuance costs

$ 1,500,000

Exercise price of warrants | $ / shares

$ 16.39

Debt instrument accrues simple interest rate

2.00%

Debt instrument maturity date

Nov. 30, 2016

Debt instrument extended maturity date

May 31, 2018

Series D Preferred Stock

Debt Instrument [Line Items]

Warrants issued to purchase shares | shares

20,136

Exercise price of warrants | $ / shares

$ 7.31

Series D Preferred Stock | CHCF Note

Debt Instrument [Line Items]

Warrants issued to purchase shares | shares

22,807

8,552

Exercise price of warrants | $ / shares

$ 6.58

Series D Convertible Preferred Stock | CHCF Note

Debt Instrument [Line Items]

Warrants issued to purchase shares | shares

22,807

8,552

Exercise price of warrants | $ / shares

$ 6.58

Pharmakon Loan Agreement

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 55,000,000

55,000,000

Number of tranches for loans | Tranche

2

Paid in kind, interest percentage

50.00%

Debt instrument, covenant description

The Company is subject to a financial covenant related to minimum trailing revenue targets that begins in June 2017, and is tested on a semi-annual basis. The minimum net revenue covenant ranges from $44.7 million for the period ended June 30, 2017 to $102.6 million for the period ended December 31, 2021. The minimum net revenues financial covenant has a 45-day equity cure period following required delivery date of the financial statements.

Debt instrument, covenant equity cure period

45 days

Debt instrument, maturity period

2021-12

Debt balance

$ 29,100,000

$ 30,800,000

29,100,000

Pharmakon Loan Agreement | Silicon Valley Bank

Debt Instrument [Line Items]

Repayment of bank debt

4,900,000

Pharmakon Loan Agreement | Scenario Forecast

Debt Instrument [Line Items]

Debt instrument, covenant compliance minimum net revenue target next twelve months

$ 44,700,000

Debt instrument, covenant compliance minimum net revenue fifth year

$ 102,600,000

Pharmakon Loan Agreement | Tranche A Loans

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 30,000,000

Debt instrument, fixed interest rate

9.50%

Debt instrument, periodic payment

quarterly

Debt instrument, interest due and payable

50.00%

Pharmakon Loan Agreement | Tranche B Loans

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 25,000,000

Loan and Security Agreement

Debt Instrument [Line Items]

Proceeds from long-term debt, net of issuance costs

$ 4,900,000

Debt borrowed additional advance

$ 5,000,000

Repayment of debt

4,900,000

Loan and Security Agreement | Series D Preferred Stock

Debt Instrument [Line Items]

Warrants issued to purchase shares | shares

20,136

Exercise price of warrants | $ / shares

$ 7.31

Warrants expiry period

2024-06

SVB Loan Agreement

Debt Instrument [Line Items]

Maximum borrowing capacity

$ 15,000,000

15,000,000

Credit facility expiration date

Dec. 4, 2018

Debt instrument variable rate basis period of net sales

12 months

Borrowing capacity description

Any principal amount outstanding under the SVB revolving credit line will bear interest at a floating rate per annum equal to the rate published by The Wall Street Journal as the “Prime Rate” plus 0.25%. The Company may borrow up to 80% of its eligible accounts receivable, up to the maximum of $15.0 million.

SVB Loan Agreement | Standby Letters of Credit | San Francisco Office

Debt Instrument [Line Items]

Letter of credit

$ 3,100,000

SVB Loan Agreement | Maximum

Debt Instrument [Line Items]

Percentage of eligible accounts receivable for borrowings

80.00%

Credit facility borrowing capacity

$ 2,900,000

$ 2,500,000

$ 2,900,000

SVB Loan Agreement | Prime Rate

Debt Instrument [Line Items]

Debt instrument interest rate spread

0.25%

Debt - Schedule of Future Minim

Debt - Schedule of Future Minimum Payments under CHCF Note and Pharmakon Loan (Details) $ in Thousands	Dec. 31, 2016USD ($)
Debt Disclosure [Abstract]
2,017	$ 1,549
2,018	4,858
2,019	3,192
2,020	19,169
2,021	17,564
Total	46,332
Less: Amount representing interest	(13,241)
Less: Amount representing debt discount and issuance costs	(864)
Present value of minimum payments	$ 32,227

Income Taxes - Additional Infor

Income Taxes - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Disclosure [Line Items]
Provision or benefit for income taxes	$ 0	$ 0	$ 0
Benefit recognized for net operating loss carryforwards	0
Benefit recognized for other deferred tax assets	0
Net operating loss carryforwards	104,600,000
Net operating loss carryforwards	58,600,000
Tax credit carryforward	1,300,000
Tax credit carryforwards available to reduce future taxable income	$ 1,200,000
Tax credit carryforwards expiration beginning year	2,027
Accrual for interest or penalties related to unrecognized tax benefits	$ 0	$ 0
Federal
Income Tax Disclosure [Line Items]
Net operating loss carry forwards expiration year	2,027
State
Income Tax Disclosure [Line Items]
Net operating loss carry forwards expiration year	2,017

Income Taxes - Reconciliation o

Income Taxes - Reconciliation of Tax Expense Computed at Statutory Federal Rate and Company's Tax Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Income Tax Expense Benefit Continuing Operations Income Tax Reconciliation [Abstract]
Tax at statutory federal rate	$ (7,107,000)	$ (7,752,000)	$ (5,365,000)
State taxes, net of federal benefit			3,000
Stock-based compensation	255,000	251,000	281,000
Other	916,000	(128,000)	166,000
Tax credits	(139,000)	(178,000)	(168,000)
Change in valuation allowance	6,075,000	7,807,000	5,083,000
Provision for income taxes	$ 0	$ 0	$ 0

Income Taxes - Tax Effects of T

Income Taxes - Tax Effects of Temporary Differences and Carryforwards of Deferred Tax Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Deferred tax assets:
Net operating loss carryforwards	$ 38,694	$ 34,714	$ 27,318
Tax credit carryforwards	1,587	1,728	1,388
Allowances and other	4,787	2,024	807
Depreciation and amortization	(207)	99	357
Total deferred tax assets	44,861	38,565	29,870
Valuation allowance	(44,861)	(38,565)	(29,870)
Net deferred tax assets	$ 0	$ 0	$ 0

Income Taxes - Reconciliation61

Income Taxes - Reconciliation of Unrecognized Tax Benefit (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation Of Unrecognized Tax Benefits Excluding Amounts Pertaining To Examined Tax Returns Roll Forward
Balance at beginning of year	$ 570	$ 460	$ 364
Additions for tax positions taken in current year	75	110	96
Decreases in balances related to prior year tax position	(29)
Balance at end of year	$ 616	$ 570	$ 460

Stockholders' Equity - Addition

Stockholders' Equity - Additional Information (Details) - USD ($)	12 Months Ended
	Dec. 31, 2016	Oct. 25, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Common stock, shares authorized	100,000,000	100,000,000	18,528,913
Common stock, par value	$ 0.001	$ 0.001	$ 0.001
Preferred stock, shares authorized			11,392,882
Dividends declared	$ 0
Convertible Preferred Stock
Class Of Stock [Line Items]
Preferred stock, shares authorized	0	5,000,000	11,392,882
Preferred stock, par value	$ 0.001	$ 0.001	$ 0.001

Stockholders' Equity - Schedule

Stockholders' Equity - Schedule Of Common Stock Shares Reserved For Future Issuance (Details) - shares	Dec. 31, 2016	Dec. 31, 2015
Class Of Stock [Line Items]
Total number of shares reserved for future issuance	7,526,060	16,689,946
Convertible Preferred Stock
Class Of Stock [Line Items]
Total number of shares reserved for future issuance		13,343,981
Convertible Preferred Stock Warrants
Class Of Stock [Line Items]
Total number of shares reserved for future issuance		328,114
Common stock warrants issued
Class Of Stock [Line Items]
Total number of shares reserved for future issuance	217,245
Options Issued and Outstanding
Class Of Stock [Line Items]
Total number of shares reserved for future issuance	2,977,218	2,685,913
RSUs Issued and Unvested
Class Of Stock [Line Items]
Total number of shares reserved for future issuance	105,529
Shares Available for Grant Under Future Stock Plans
Class Of Stock [Line Items]
Total number of shares reserved for future issuance	4,226,068	331,938

Convertible Preferred Stock - A

Convertible Preferred Stock - Additional Information(Details) - USD ($)	Oct. 19, 2016	Oct. 31, 2016	Dec. 31, 2016
Class Of Stock [Line Items]
Dividends declared			$ 0
Proceeds from stock issuance, net of underwriting discounts and commissions			$ 114,436,000
Minimum
Class Of Stock [Line Items]
Percentage of outstanding preferred shares and holders voting together as single class on an as-if converted to common stock basis			63.00%
Initial Public Offering
Class Of Stock [Line Items]
Proceeds from stock issuance, net of underwriting discounts and commissions	$ 110,700,000
Convertible Preferred Stock | Initial Public Offering
Class Of Stock [Line Items]
Conversion of convertible preferred stock to common stock in connection with initial public offering, Shares		(11,077,505)	(11,077,505)
Series E Convertible Preferred Stock
Class Of Stock [Line Items]
Dividend rate per share			$ 0.71
Percentage of liquidation preference on purchase price plus any declared but unpaid dividends			100.00%
Convertible preferred stock conversion percentage			100.00%
Convertible preferred stock conversion basis			one-for-one basis
Series D Convertible Preferred Stock
Class Of Stock [Line Items]
Dividend rate per share			$ 0.59
Percentage of liquidation preference on purchase price plus any declared but unpaid dividends			150.00%
Convertible preferred stock conversion percentage			100.00%
Convertible preferred stock conversion basis			one-for-one basis
Series B Convertible Preferred Stock
Class Of Stock [Line Items]
Dividend rate per share			$ 1.29
Percentage of liquidation preference on purchase price plus any declared but unpaid dividends			100.00%
Convertible preferred stock conversion percentage			49.89053%
Convertible preferred stock conversion basis			one-for-2.00438849
Series C Convertible Preferred Stock
Class Of Stock [Line Items]
Dividend rate per share			$ 1.29
Percentage of liquidation preference on purchase price plus any declared but unpaid dividends			150.00%
Convertible preferred stock conversion percentage			44.50666%
Convertible preferred stock conversion basis			one-for-2.24685484
Series A Convertible Preferred Stock
Class Of Stock [Line Items]
Dividend rate per share			$ 0.47
Percentage of liquidation preference on purchase price plus any declared but unpaid dividends			100.00%
Convertible preferred stock conversion percentage			100.00%
Convertible preferred stock conversion basis			one-for-one basis
Common Stock
Class Of Stock [Line Items]
Dividend rate per share			$ 0
Common Stock | Initial Public Offering
Class Of Stock [Line Items]
Conversion of convertible preferred stock to common stock in connection with initial public offering, Shares		13,375,333	13,375,333
Common Stock | Initial Public Offering | Maximum
Class Of Stock [Line Items]
Common stock offering price per share			$ 17.65
Proceeds from stock issuance, net of underwriting discounts and commissions			$ 40,000,000

Convertible Preferred Stock - S

Convertible Preferred Stock - Summary of Convertible Preferred Stock Offerings (Details) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2015USD ($)$ / sharesshares
Temporary Equity [Line Items]
Temporary equity, shares authorized	11,392,882
Temporary equity, shares issued	11,046,146
Temporary equity, shares outstanding	11,046,146
Number of shares converted into common stock	13,343,981
Temporary equity, liquidation preference | $	$ 117,495
Convertible preferred stock, Proceeds Net of Issuance Costs | $	$ 97,096
Series A Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, Original Issue Price | $ / shares	$ 5.67
Temporary equity, shares authorized	3,415,649
Temporary equity, shares issued	3,390,963
Temporary equity, shares outstanding	3,390,963
Number of shares converted into common stock	3,390,963
Temporary equity, liquidation preference | $	$ 19,236
Convertible preferred stock, Proceeds Net of Issuance Costs | $	$ 19,134
Series B Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, Original Issue Price | $ / shares	$ 16.39
Temporary equity, shares authorized	623,254
Temporary equity, shares issued	610,134
Temporary equity, shares outstanding	610,134
Number of shares converted into common stock	1,222,944
Temporary equity, liquidation preference | $	$ 10,000
Convertible preferred stock, Proceeds Net of Issuance Costs | $	$ 9,855
Series C Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, Original Issue Price | $ / shares	$ 16.39
Temporary equity, shares authorized	1,360,582
Temporary equity, shares issued	1,351,423
Temporary equity, shares outstanding	1,351,423
Number of shares converted into common stock	3,036,448
Temporary equity, liquidation preference | $	$ 33,224
Convertible preferred stock, Proceeds Net of Issuance Costs | $	$ 21,953
Series D Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, Original Issue Price | $ / shares	$ 7.31
Temporary equity, shares authorized	2,627,595
Temporary equity, shares issued	2,327,897
Temporary equity, shares outstanding	2,327,897
Number of shares converted into common stock	2,327,897
Temporary equity, liquidation preference | $	$ 25,516
Convertible preferred stock, Proceeds Net of Issuance Costs | $	$ 16,843
Series E Convertible Preferred Stock
Temporary Equity [Line Items]
Convertible preferred stock, Original Issue Price | $ / shares	$ 8.77
Temporary equity, shares authorized	3,365,802
Temporary equity, shares issued	3,365,729
Temporary equity, shares outstanding	3,365,729
Number of shares converted into common stock	3,365,729
Temporary equity, liquidation preference | $	$ 29,519
Convertible preferred stock, Proceeds Net of Issuance Costs | $	$ 29,311

Preferred Stock Warrant Liabi66

Preferred Stock Warrant Liabilities - Additional Information (Details) - USD ($)

Oct. 26, 2016

Jun. 30, 2015

Jun. 30, 2014

Apr. 30, 2013

Dec. 31, 2012

Nov. 30, 2012

Feb. 28, 2011

May 31, 2010

Nov. 30, 2009

Dec. 31, 2016

Dec. 31, 2015

Dec. 31, 2014

Mar. 27, 2013

Class Of Warrant Or Right [Line Items]

Change in fair value of preferred stock warrant liabilities

$ 2,123,000

$ 111,000

$ 291,000

CHCF Note

Class Of Warrant Or Right [Line Items]

Exercise price of warrants

$ 16.39

Fair value assumptions, expected volatility rate

60.00%

Fair value assumptions, risk free interest rate

1.60%

Fair value assumptions, expected term

10 years

Change in fair value of preferred stock warrant liabilities

$ 153,000

$ 50,000

14,000

24,000

Warrant exercise period

Oct. 3, 2016

Warrant [Member]

Class Of Warrant Or Right [Line Items]

Change in fair value of preferred stock warrant liabilities

$ 237,000

14,000

(4,000)

Warrant exercise period

Oct. 26, 2016

Issuance of common stock upon exercise of warrants, Shares

7,310

Fair value warrants recorded as debt discount

$ 98,000

Fair value assumptions, discount rate

30.00%

Warrant exercised

10,068

Warrants outstanding

10,068

Warrant [Member] | CHCF Note

Class Of Warrant Or Right [Line Items]

Change in fair value of preferred stock warrant liabilities

$ 19,000

6,000

Warrant exercise period

Oct. 3, 2016

Fair value warrants recorded as debt discount

$ 44,000

Warrant [Member] | CHCF Note | Minimum

Class Of Warrant Or Right [Line Items]

Fair value assumptions, discount rate

13.00%

Warrant [Member] | CHCF Note | Maximum

Class Of Warrant Or Right [Line Items]

Fair value assumptions, discount rate

27.00%

Series D Preferred Stock

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

20,136

Exercise price of warrants

$ 7.31

Series D Preferred Stock | CHCF Note

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

8,552

22,807

Exercise price of warrants

$ 6.58

Series D Preferred Stock | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants expiry period

Jun. 30, 2024

Series D Preferred Stock | Warrant [Member] | CHCF Note

Class Of Warrant Or Right [Line Items]

Description of warrants expiration period

expire at the earlier of November 2022 or a liquidation event

Series C Convertible Preferred Stock | CHCF Note

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

150,000

Description of warrants expiration period

expire at the earlier of November 2022 or a liquidation event

Warrants issued to purchase preferred stock

9,152

Series C Convertible Preferred Stock | CHCF Note | Minimum

Class Of Warrant Or Right [Line Items]

Proceeds from issuance of warrants

$ 500,000

2009 Loan Agreement One | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Fair value assumptions, expected volatility rate

70.00%

Fair value assumptions, risk free interest rate

2.20%

Fair value assumptions, exercise price

$ 5.67

Fair value assumptions, expected term

10 years

Fair value warrants recorded as debt issuance cost

$ 68,000

Change in fair value of preferred stock warrant liabilities

$ 182,000

38,000

28,000

Warrant exercise period

Oct. 26, 2016

Issuance of common stock upon exercise of warrants, Shares

12,491

2009 Loan Agreement One | Series A Convertible Preferred Stock

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

15,865

Exercise price of warrants

$ 5.67

2009 Loan Agreement One | Series A Convertible Preferred Stock | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants expiry period

Nov. 30, 2019

2009 Loan Agreement Two | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Fair value assumptions, expected volatility rate

70.00%

Fair value assumptions, risk free interest rate

2.20%

Fair value assumptions, exercise price

$ 5.67

Fair value assumptions, expected term

10 years

Change in fair value of preferred stock warrant liabilities

$ 101,000

22,000

15,000

Warrant exercise period

Oct. 26, 2016

Issuance of common stock upon exercise of warrants, Shares

6,939

Fair value warrants recorded as debt discount

$ 38,000

2009 Loan Agreement Two | Series A Convertible Preferred Stock

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

8,813

Exercise price of warrants

$ 5.67

2009 Loan Agreement Two | Series A Convertible Preferred Stock | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants expiry period

Nov. 30, 2019

2010 Loan Agreement | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Fair value assumptions, expected volatility rate

60.00%

Fair value assumptions, risk free interest rate

2.80%

Fair value assumptions, exercise price

$ 16.39

Fair value assumptions, expected term

9 years 6 months

Change in fair value of preferred stock warrant liabilities

$ 14,000

5,000

4,000

Warrant exercise period

Oct. 26, 2016

Issuance of common stock upon exercise of warrants, Shares

2,119

Fair value warrants recorded as debt discount

$ 19,000

2010 Loan Agreement | Series B Convertible Preferred Stock

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

1,525

Exercise price of warrants

$ 16.39

2010 Loan Agreement | Series B Convertible Preferred Stock | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants expiry period

Nov. 30, 2019

2011 Loan Agreement | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Fair value assumptions, expected volatility rate

60.00%

Fair value assumptions, risk free interest rate

3.40%

Fair value assumptions, exercise price

$ 16.39

Fair value assumptions, expected term

10 years

Change in fair value of preferred stock warrant liabilities

$ 104,000

42,000

29,000

Warrant exercise period

Oct. 26, 2016

Issuance of common stock upon exercise of warrants, Shares

16,113

Fair value warrants recorded as debt discount

$ 121,000

2011 Loan Agreement | Series B Convertible Preferred Stock

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

11,592

Exercise price of warrants

$ 16.39

2011 Loan Agreement | Series B Convertible Preferred Stock | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants expiry period

Feb. 28, 2021

2012 Loan Agreement

Class Of Warrant Or Right [Line Items]

Exercise price of warrants

$ 0.01

2012 Loan Agreement | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Change in fair value of preferred stock warrant liabilities

$ 1,199,000

(42,000)

178,000

Warrants term

7 years

2012 Loan Agreement | Series D Preferred Stock

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

207,177

2013 Loan Agreement | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Change in fair value of preferred stock warrant liabilities

$ 217,000

$ 12,000

$ 19,000

Warrant exercise period

Oct. 26, 2016

Issuance of common stock upon exercise of warrants, Shares

13,414

Fair value warrants recorded as debt discount

$ 72,000

Fair value assumptions, discount rate

22.00%

2013 Loan Agreement | Series D Preferred Stock

Class Of Warrant Or Right [Line Items]

Warrants issued to purchase shares

18,474

Exercise price of warrants

$ 7.31

2013 Loan Agreement | Series D Preferred Stock | Warrant [Member]

Class Of Warrant Or Right [Line Items]

Warrants expiry period

Apr. 30, 2023

Stock Incentive Plans - Additio

Stock Incentive Plans - Additional Information (Details)	1 Months Ended	12 Months Ended
	Oct. 31, 2016shares	Dec. 31, 2016USD ($)Period$ / sharesshares	Dec. 31, 2015USD ($)$ / sharesshares	Dec. 31, 2014USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Options granted during the period		361,385	915,080	429,474
Shares available for future issuance		7,526,060	16,689,946
Expected term		6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Expected dividend yield		0.00%	0.00%	0.00%
Weighted-average grant date fair value of options | $ / shares		$ 8.76	$ 4.08	$ 2.20
Stock option, intrinsic value | $		$ 654,000	$ 237,000	$ 96,000
Estimated grant date fair value of stock option vested | $		$ 1,800,000	$ 1,100,000	$ 869,000
2006 Equity Incentive Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option plan, description		Options under the Plan may be granted for periods of up to ten years and at prices no less than 85% of the estimated fair value of the shares on the date of grant as determined by the board of directors, provided, however, that (i) the exercise price of an ISO and NSO shall not be less than 100% and 85% of the estimated fair value of the shares on the date of grant, respectively, and (ii) the exercise price of an ISO and NSO granted to a 10% stockholder shall not be less than 110% of the estimated fair value of the shares on the date of grant.
Stock option vesting term		3 years
2006 Equity Incentive Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, period for grant		10 years
2006 Equity Incentive Plan | Maximum | ISO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term		5 years
2006 Equity Incentive Plan | Maximum | Other Options
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option vesting term		10 years
2006 Equity Incentive Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, purchase price percentage of estimated fair value		85.00%
Percentage of voting power of all classes of stock		10.00%
2006 Equity Incentive Plan | Minimum | ISO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, purchase price percentage of estimated fair value		100.00%
2006 Equity Incentive Plan | Minimum | NSO
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, purchase price percentage of estimated fair value		85.00%
2006 Equity Incentive Plan | Minimum | ISO and NSO Granted to a 10% Stockholder
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, purchase price percentage of estimated fair value		110.00%
2016 Plan
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option plan, description		On the first day of each year beginning with 2017, the 2016 Plan authorizes an annual increase of the least of 3,865,000 shares, 5% of outstanding shares on the last day of the immediately preceding fiscal year or an amount as determined by the Company's Board of Directors.
Effective date		Oct. 19, 2016
Options granted during the period	0
Shares available for future issuance	3,865,000	3,743,037
Percentage of outstanding shares increased annually under the plan	5.00%
2016 Plan | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, period for grant		10 years
2016 Plan | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of stock option exercise price of fair market value of common stock	100.00%
Employee Stock Purchase Program (“ESPP”)
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Stock option, purchase price percentage of estimated fair value	85.00%
Effective date		Oct. 19, 2016
Shares available for future issuance	483,031	483,031
Percentage of outstanding shares increased annually under the plan	1.50%
Increase in shares available for future issuance	966,062
Offering period		12 months
Number of purchase period | Period		2
Purchase period		6 months
Common stock issued to employees		0
Expected volatility, minimum		53.21%
Expected volatility, maximum		57.69%
Risk-free interest rate, minimum		0.52%
Risk-free interest rate, maximum		0.68%
Expected dividend yield		0.00%
Employee Stock Purchase Program (“ESPP”) | Maximum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Percentage of payroll deductions of eligible compensation	15.00%
Expected term		1 year 1 month 13 days
Employee Stock Purchase Program (“ESPP”) | Minimum
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected term		7 months 10 days

Stock Incentive Plans - Summary

Stock Incentive Plans - Summary of Share-based Awards Available for Grant (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Shares Available for Grant, Beginning balance	331,938	347,814	382,071
Shares Available for Grant, Additional options authorized	3,865,000	781,954	356,979
Shares Available for Grant, Options granted	(466,914)	(915,080)	(429,474)
Shares Available for Grant, Options forfeited	13,013	117,250	38,238
Shares Available for Grant, Ending balance	3,743,037	331,938	347,814

Stock Incentive Plans - Summa69

Stock Incentive Plans - Summary of Stock Option Activity Under 2006 and 2016 Plans, Including Grants To Nonemployees (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Options Outstanding, Beginning balance	2,685,913	1,972,383	1,620,129
Options granted	361,385	915,080	429,474
Options exercised	(57,067)	(84,300)	(38,982)
Options forfeited	(13,013)	(117,250)	(38,238)
Options Outstanding, Ending balance	2,977,218	2,685,913	1,972,383	1,620,129
Options exercisable	1,940,798
Options vested and expected to vest	2,912,854
Options Outstanding, Weighted Average Exercise Price Per Share, Beginning Balance	$ 4.81	$ 3.70	$ 3.59
Options Outstanding, Weighted Average Exercise Price Per Share, Options granted	15.65	3.98	3.86
Options Outstanding, Weighted Average Exercise Price Per Share, Options exercised	2.33	3.71	1.30
Options Outstanding, Weighted Average Exercise Price Per Share, Options forfeited	6.92	3.94	3.34
Options Outstanding, Weighted Average Exercise Price Per Share, Ending Balance	6.16	$ 4.81	$ 3.70	$ 3.59
Options Outstanding, Weighted Average Exercise Price Per Share, Exercisable	4.35
Options Outstanding, Weighted Average Exercise Price Per Share, vested and expected to vest	$ 6.06
Options Outstanding, Weighted- Average Remaining Contractual Life (years)	6 years 11 months 5 days	7 years 7 months 17 days	7 years 10 months 10 days	8 years 2 months 12 days
Options exercisable, Weighted- Average Remaining Contractual Life (years)	6 years 3 months
Options vested and expected to vest, Weighted- Average Remaining Contractual Life (years)	7 years 22 days
Options Outstanding, Aggregate Intrinsic Value	$ 70,979	$ 11,589	$ 4,191
Options exercisable, Aggregate Intrinsic Value	49,775
Options vested and expected to vest, Aggregate Intrinsic Value	$ 69,746

Stock Incentive Plans - Summa70

Stock Incentive Plans - Summary of Nonvested Restricted Stock Units ("RSUs") (Details) - Restricted Stock Units ("RSUs") $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016USD ($)$ / sharesshares
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Shares Underlying RSUs, Nonvested, Beginning balance | shares	0
Shares Underlying RSUs, Granted | shares	105,529
Shares Underlying RSUs, Nonvested, Ending balance | shares	105,529
Shares Underlying RSUs, Nonvested Outstanding, Weighted Average Grant Date Fair Value, Beginning Balance | $ / shares	$ 0
Shares Underlying RSUs, Granted, Weighted Average Grant Date Fair Value | $ / shares	27.39
Shares Underlying RSUs, Nonvested Outstanding, Weighted Average Grant Date Fair Value, Ending Balance | $ / shares	$ 27.39
Shares Underlying RSUs, Nonvested Weighted Remaining Vesting Period (in years)	2 years 1 month 13 days
Shares Underlying RSUs, Nonvested, Aggregate Intrinsic Value | $	$ 3,166

Stock-Based Compensation - Sche

Stock-Based Compensation - Schedule of Fair Value of Employee Stock Options Estimated Using Weighted Average Assumptions (Details)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Disclosure Of Compensation Related Costs Sharebased Payments [Abstract]
Expected term (in years)	6 years 1 month 6 days	6 years 1 month 6 days	6 years 1 month 6 days
Expected volatility	60.00%	60.00%	60.00%
Risk-free interest rate	1.42%	1.76%	2.08%
Dividend yield	0.00%	0.00%	0.00%

Stock-Based Compensation - Addi

Stock-Based Compensation - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Expected dividend yield	0.00%	0.00%	0.00%
Total unamortized compensation costs, net of estimated forfeitures related to unvested stock options	$ 5.1
Unamortized compensation costs related to unvested stock options, expected period of recognition	2 years 10 months 24 days
Restricted Stock Units ("RSUs")
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unamortized compensation costs, net of estimated forfeitures related to unvested stock options	$ 2.8
Unamortized compensation costs related to unvested stock options, expected period of recognition	2 years 1 month 6 days
ESPP
Share Based Compensation Arrangement By Share Based Payment Award [Line Items]
Total unamortized compensation costs, net of estimated forfeitures related to unvested stock options	$ 1.9
Unamortized compensation costs related to unvested stock options, expected period of recognition	11 months 1 day

Stock-Based Compensation - Summ

Stock-Based Compensation - Summary of Total Stock-Based Compensation Expense for Options, RSUs and ESPP Included in Consolidated Statements of Operations and Comprehensive Loss (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,871	$ 1,410	$ 828
Cost of Revenue
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	17	17	15
Research and development
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	203	165	80
Selling, general and administrative
Employee Service Share Based Compensation Allocation Of Recognized Period Costs [Line Items]
Total stock-based compensation expense	$ 1,651	$ 1,228	$ 733

Net Loss Per Common Share - Com

Net Loss Per Common Share - Computation of Basic and Diluted Net Loss per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator:
Net Loss	$ (6,266)	$ (4,075)	$ (4,436)	$ (6,126)	$ (7,702)	$ (5,746)	$ (4,959)	$ (4,392)	$ (20,903)	$ (22,799)	$ (15,832)
Denominator:
Weighted-average shares used to compute net loss per common share, basic and diluted									5,285,847	1,376,106	1,314,294
Net loss per common share, basic and diluted	$ (0.37)	$ (2.80)	$ (3.12)	$ (4.34)	$ (5.46)	$ (4.07)	$ (3.66)	$ (3.31)	$ (3.95)	$ (16.57)	$ (12.05)

Net Loss Per Common Share - Sch

Net Loss Per Common Share - Schedule of Anti-dilutive Securities Excluded from Diluted Net Loss per Common Share (Details) - shares	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per common share	3,299,992	16,358,008
Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per common share		13,343,981
Options to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per common share	2,977,218	2,685,913
RSUs Issued and Unvested
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per common share	105,529
Warrants to Purchase Convertible Preferred Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per common share		328,114
Warrants to Purchase Common Stock
Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items]
Anti-dilutive securities excluded from diluted net loss per common share	217,245

Selected Quarterly Financial 76

Selected Quarterly Financial Data (Unaudited) - Schedule of Quarterly Financial Information (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 18,704	$ 16,780	$ 15,734	$ 12,854	$ 10,854	$ 9,344	$ 8,887	$ 7,055	$ 64,072	$ 36,140	$ 21,749
Gross profit	12,918	11,498	10,578	8,195	6,693	5,596	5,269	3,882	43,189	21,440	11,158
Net Loss	$ (6,266)	$ (4,075)	$ (4,436)	$ (6,126)	$ (7,702)	$ (5,746)	$ (4,959)	$ (4,392)	$ (20,903)	$ (22,799)	$ (15,832)
Net loss per common share, basic and diluted	$ (0.37)	$ (2.80)	$ (3.12)	$ (4.34)	$ (5.46)	$ (4.07)	$ (3.66)	$ (3.31)	$ (3.95)	$ (16.57)	$ (12.05)